diff --git a/docs/slate-formats.md b/docs/slate-formats.md
new file mode 100644
index 00000000000..7bb2fc9c5ff
--- /dev/null
+++ b/docs/slate-formats.md
@@ -0,0 +1,88 @@
+Guide to data types used by the Slate-based Rich Text Editor
+------------------------------------------------------------
+
+We always store the Slate editor state in its Value form.
+
+The schema for the Value is the same whether the editor is in MD or rich text mode, and is currently (rather arbitrarily)
+dictated by the schema expected by slate-md-serializer, simply because it was the only bit of the pipeline which
+has opinions on the schema. (slate-html-serializer lets you define how to serialize whatever schema you like).
+
+The BLOCK_TAGS and MARK_TAGS give the mapping from HTML tags to the schema's node types (for blocks, which describe
+block content like divs, and marks, which describe inline formatted sections like spans).
+
+We use <p/> as the parent tag for the message (XXX: although some tags are technically not allowed to be nested within p's)
+
+Various conversions are performed as content is moved between HTML, MD, and plaintext representations of HTML and MD.
+
+The primitives used are:
+
+ * Markdown.js - models commonmark-formatted MD strings (as entered by the composer in MD mode)
+   * toHtml() - renders them to HTML suitable for sending on the wire
+   * isPlainText() - checks whether the parsed MD contains anything other than simple text.
+   * toPlainText() - renders MD to plain text in order to remove backslashes.  Only works if the MD is already plaintext (otherwise it just emits HTML)
+
+ * slate-html-serializer
+   * converts Values to HTML (serialising) using our schema rules
+   * converts HTML to Values (deserialising) using our schema rules
+
+ * slate-md-serializer
+   * converts rich Values to MD strings (serialising) but using a non-commonmark generic MD dialect.
+   * This should use commonmark, but we use the serializer here for expedience rather than writing a commonmark one.
+
+ * slate-plain-serializer
+  * converts Values to plain text strings (serialising them) by concatenating the strings together
+  * converts Values from plain text strings (deserialiasing them).
+  * Used to initialise the editor by deserializing "" into a Value. Apparently this is the idiomatic way to initialise a blank editor.
+  * Used (as a bodge) to turn a rich text editor into a MD editor, when deserialising the converted MD string of the editor into a value
+
+ * PlainWithPillsSerializer
+  * A fork of slate-plain-serializer which is aware of Pills (hence the name) and Emoji.
+  * It can be configured to output Pills as:
+    * "plain": Pills are rendered via their 'completion' text - e.g. 'Matthew'; used for sending messages)
+    * "md": Pills are rendered as MD, e.g. [Matthew](https://matrix.to/#/@matthew:matrix.org) )
+    * "id": Pills are rendered as IDs, e.g. '@matthew:matrix.org' (used for authoring / commands)
+  * Emoji nodes are converted to inline utf8 emoji.
+
+The actual conversion transitions are:
+
+ * Quoting:
+   * The message being quoted is taken as HTML
+   * ...and deserialised into a Value
+   * ...and then serialised into MD via slate-md-serializer if the editor is in MD mode
+
+ * Roundtripping between MD and rich text editor mode
+   * From MD to richtext (mdToRichEditorState):
+     * Serialise the MD-format Value to a MD string (converting pills to MD) with PlainWithPillsSerializer in 'md' mode
+     * Convert that MD string to HTML via Markdown.js
+     * Deserialise that Value to HTML via slate-html-serializer
+   * From richtext to MD (richToMdEditorState):
+     * Serialise the richtext-format Value to a MD string with slate-md-serializer (XXX: this should use commonmark)
+     * Deserialise that to a plain text value via slate-plain-serializer
+
+ * Loading history in one format into an editor which is in the other format
+   * Uses the same functions as for roundtripping
+
+ * Scanning the editor for a slash command
+   * If the editor is a single line node starting with /, then serialize it to a string with PlainWithPillsSerializer in 'id' mode
+     So that pills get converted to IDs suitable for commands being passed around
+
+ * Sending messages
+   * In RT mode:
+     * If there is rich content, serialize the RT-format Value to HTML body via slate-html-serializer
+     * Serialize the RT-format Value to the plain text fallback via PlainWithPillsSerializer in 'plain' mode
+   * In MD mode:
+     * Serialize the MD-format Value into an MD string with PlainWithPillsSerializer in 'md' mode
+     * Parse the string with Markdown.js
+     * If it contains no formatting:
+       * Send as plaintext (as taken from Markdown.toPlainText())
+     * Otherwise
+       * Send as HTML (as taken from Markdown.toHtml())
+       * Serialize the RT-format Value to the plain text fallback via PlainWithPillsSerializer in 'plain' mode
+
+ * Pasting HTML
+   * Deserialize HTML to a RT Value via slate-html-serializer
+   * In RT mode, insert it straight into the editor as a fragment
+   * In MD mode, serialise it to an MD string via slate-md-serializer and then insert the string into the editor as a fragment.
+
+The various scenarios and transitions could be drawn into a pretty diagram if one felt the urge, but hopefully the above
+gives sufficient detail on how it's all meant to work.
\ No newline at end of file
diff --git a/package.json b/package.json
index d639a4e51ce..661febf6af5 100644
--- a/package.json
+++ b/package.json
@@ -84,7 +84,7 @@
     "react-beautiful-dnd": "^4.0.1",
     "react-dom": "^15.6.0",
     "react-gemini-scrollbar": "matrix-org/react-gemini-scrollbar#5e97aef",
-    "slate": "^0.33.4",
+    "slate": "0.33.4",
     "slate-react": "^0.12.4",
     "slate-html-serializer": "^0.6.1",
     "slate-md-serializer": "matrix-org/slate-md-serializer#f7c4ad3",
diff --git a/src/ComposerHistoryManager.js b/src/ComposerHistoryManager.js
index e78fbcdc3b8..0164e6c4cde 100644
--- a/src/ComposerHistoryManager.js
+++ b/src/ComposerHistoryManager.js
@@ -51,8 +51,8 @@ class HistoryItem {
 export default class ComposerHistoryManager {
     history: Array<HistoryItem> = [];
     prefix: string;
-    lastIndex: number = 0;
-    currentIndex: number = 0;
+    lastIndex: number = 0; // used for indexing the storage
+    currentIndex: number = 0; // used for indexing the loaded validated history Array
 
     constructor(roomId: string, prefix: string = 'mx_composer_history_') {
         this.prefix = prefix + roomId;
@@ -69,18 +69,19 @@ export default class ComposerHistoryManager {
             }
         }
         this.lastIndex = this.currentIndex;
+        // reset currentIndex to account for any unserialisable history
+        this.currentIndex = this.history.length;
     }
 
     save(value: Value, format: MessageFormat) {
         const item = new HistoryItem(value, format);
         this.history.push(item);
-        this.currentIndex = this.lastIndex + 1;
+        this.currentIndex = this.history.length;
         sessionStorage.setItem(`${this.prefix}[${this.lastIndex++}]`, JSON.stringify(item.toJSON()));
     }
 
     getItem(offset: number): ?HistoryItem {
-        this.currentIndex = _clamp(this.currentIndex + offset, 0, this.lastIndex - 1);
-        const item = this.history[this.currentIndex];
-        return item;
+        this.currentIndex = _clamp(this.currentIndex + offset, 0, this.history.length - 1);
+        return this.history[this.currentIndex];
     }
 }
diff --git a/src/HtmlUtils.js b/src/HtmlUtils.js
index ccfecb80812..09ce1187d50 100644
--- a/src/HtmlUtils.js
+++ b/src/HtmlUtils.js
@@ -112,42 +112,6 @@ export function charactersToImageNode(alt, useSvg, ...unicode) {
     />;
 }
 
-/*
-export function processHtmlForSending(html: string): string {
-    const contentDiv = document.createElement('div');
-    contentDiv.innerHTML = html;
-
-    if (contentDiv.children.length === 0) {
-        return contentDiv.innerHTML;
-    }
-
-    let contentHTML = "";
-    for (let i=0; i < contentDiv.children.length; i++) {
-        const element = contentDiv.children[i];
-        if (element.tagName.toLowerCase() === 'p') {
-            contentHTML += element.innerHTML;
-            // Don't add a <br /> for the last <p>
-            if (i !== contentDiv.children.length - 1) {
-                contentHTML += '<br />';
-            }
-        } else if (element.tagName.toLowerCase() === 'pre') {
-            // Replace "<br>\n" with "\n" within `<pre>` tags because the <br> is
-            // redundant. This is a workaround for a bug in draft-js-export-html:
-            //   https://github.com/sstur/draft-js-export-html/issues/62
-            contentHTML += '<pre>' +
-                element.innerHTML.replace(/<br>\n/g, '\n').trim() +
-                '</pre>';
-        } else {
-            const temp = document.createElement('div');
-            temp.appendChild(element.cloneNode(true));
-            contentHTML += temp.innerHTML;
-        }
-    }
-
-    return contentHTML;
-}
-*/
-
 /*
  * Given an untrusted HTML string, return a React node with an sanitized version
  * of that HTML.
diff --git a/src/Markdown.js b/src/Markdown.js
index 9d9a8621c9f..dc0d5962fdd 100644
--- a/src/Markdown.js
+++ b/src/Markdown.js
@@ -180,14 +180,6 @@ export default class Markdown {
             if (is_multi_line(node) && node.next) this.lit('\n\n');
         };
 
-        // convert MD links into console-friendly ' < http://foo >' style links
-        // ...except given this function never gets called with links, it's useless.
-        // renderer.link = function(node, entering) {
-        //     if (!entering) {
-        //         this.lit(` < ${node.destination} >`);
-        //     }
-        // };
-
         return renderer.render(this.parsed);
     }
 }
diff --git a/src/autocomplete/Autocompleter.js b/src/autocomplete/Autocompleter.js
index b3c20a713c4..7f91676cc3a 100644
--- a/src/autocomplete/Autocompleter.js
+++ b/src/autocomplete/Autocompleter.js
@@ -29,9 +29,9 @@ import NotifProvider from './NotifProvider';
 import Promise from 'bluebird';
 
 export type SelectionRange = {
-    beginning: boolean,
-    start: number,
-    end: number
+    beginning: boolean, // whether the selection is in the first block of the editor or not
+    start: number, // byte offset relative to the start anchor of the current editor selection.
+    end: number, // byte offset relative to the end anchor of the current editor selection.
 };
 
 export type Completion = {
diff --git a/src/autocomplete/CommandProvider.js b/src/autocomplete/CommandProvider.js
index 0377ff33952..850d97ab712 100644
--- a/src/autocomplete/CommandProvider.js
+++ b/src/autocomplete/CommandProvider.js
@@ -43,7 +43,7 @@ export default class CommandProvider extends AutocompleteProvider {
 
         let matches = [];
         // check if the full match differs from the first word (i.e. returns false if the command has args)
-        if (command[0] !== command[1]) { 
+        if (command[0] !== command[1]) {
             // The input looks like a command with arguments, perform exact match
             const name = command[1].substr(1); // strip leading `/`
             if (CommandMap[name]) {
diff --git a/src/autocomplete/UserProvider.js b/src/autocomplete/UserProvider.js
index 156aac2eb8c..7998337e2e5 100644
--- a/src/autocomplete/UserProvider.js
+++ b/src/autocomplete/UserProvider.js
@@ -111,7 +111,7 @@ export default class UserProvider extends AutocompleteProvider {
                     // relies on the length of the entity === length of the text in the decoration.
                     completion: user.rawDisplayName.replace(' (IRC)', ''),
                     completionId: user.userId,
-                    suffix: (selection.beginning && range.start === 0) ? ': ' : ' ',
+                    suffix: (selection.beginning && selection.start === 0) ? ': ' : ' ',
                     href: makeUserPermalink(user.userId),
                     component: (
                         <PillCompletion
diff --git a/src/components/structures/ContextualMenu.js b/src/components/structures/ContextualMenu.js
index adc8dfd11c2..7295fd45d38 100644
--- a/src/components/structures/ContextualMenu.js
+++ b/src/components/structures/ContextualMenu.js
@@ -220,7 +220,8 @@ export default class ContextualMenu extends React.Component {
                 { chevron }
                 <ElementClass {...props} onFinished={props.closeMenu} onResize={props.windowResize} />
             </div>
-            { props.hasBackground && <div className="mx_ContextualMenu_background" onClick={props.closeMenu} onContextMenu={this.onContextMenu} /> }
+            { props.hasBackground && <div className="mx_ContextualMenu_background"
+                                          onClick={props.closeMenu} onContextMenu={this.onContextMenu} /> }
             <style>{ chevronCSS }</style>
         </div>;
     }
diff --git a/src/components/views/rooms/EventTile.js b/src/components/views/rooms/EventTile.js
index 9ed73c39b16..fff04d476d9 100644
--- a/src/components/views/rooms/EventTile.js
+++ b/src/components/views/rooms/EventTile.js
@@ -56,7 +56,7 @@ const stateEventTileTypes = {
     'm.room.topic': 'messages.TextualEvent',
     'm.room.power_levels': 'messages.TextualEvent',
     'm.room.pinned_events': 'messages.TextualEvent',
-    'm.room.server_acl' : 'messages.TextualEvent',
+    'm.room.server_acl': 'messages.TextualEvent',
 
     'im.vector.modular.widgets': 'messages.TextualEvent',
 };
diff --git a/src/components/views/rooms/MessageComposer.js b/src/components/views/rooms/MessageComposer.js
index 746f3909f2f..657fd463fd5 100644
--- a/src/components/views/rooms/MessageComposer.js
+++ b/src/components/views/rooms/MessageComposer.js
@@ -16,7 +16,7 @@ limitations under the License.
 */
 import React from 'react';
 import PropTypes from 'prop-types';
-import { _t } from '../../../languageHandler';
+import { _t, _td } from '../../../languageHandler';
 import CallHandler from '../../../CallHandler';
 import MatrixClientPeg from '../../../MatrixClientPeg';
 import Modal from '../../../Modal';
@@ -26,6 +26,17 @@ import RoomViewStore from '../../../stores/RoomViewStore';
 import SettingsStore, {SettingLevel} from "../../../settings/SettingsStore";
 import Stickerpicker from './Stickerpicker';
 
+const formatButtonList = [
+    _td("bold"),
+    _td("italic"),
+    _td("deleted"),
+    _td("underlined"),
+    _td("inline-code"),
+    _td("block-quote"),
+    _td("bulleted-list"),
+    _td("numbered-list"),
+];
+
 export default class MessageComposer extends React.Component {
     constructor(props, context) {
         super(props, context);
@@ -322,18 +333,17 @@ export default class MessageComposer extends React.Component {
         let formatBar;
         if (this.state.showFormatting && this.state.inputState.isRichTextEnabled) {
             const {marks, blockType} = this.state.inputState;
-            const formatButtons = ["bold", "italic", "deleted", "underlined", "inline-code", "block-quote", "bulleted-list", "numbered-list"].map(
-                (name) => {
-                    const active = marks.some(mark => mark.type === name) || blockType === name;
-                    const suffix = active ? '-on' : '';
-                    const onFormatButtonClicked = this.onFormatButtonClicked.bind(this, name);
-                    const className = 'mx_MessageComposer_format_button mx_filterFlipColor';
-                    return <img className={className}
-                                title={_t(name)}
-                                onMouseDown={onFormatButtonClicked}
-                                key={name}
-                                src={`img/button-text-${name}${suffix}.svg`}
-                                height="17" />;
+            const formatButtons = formatButtonList.map((name) => {
+                const active = marks.some(mark => mark.type === name) || blockType === name;
+                const suffix = active ? '-on' : '';
+                const onFormatButtonClicked = this.onFormatButtonClicked.bind(this, name);
+                const className = 'mx_MessageComposer_format_button mx_filterFlipColor';
+                return <img className={className}
+                            title={_t(name)}
+                            onMouseDown={onFormatButtonClicked}
+                            key={name}
+                            src={`img/button-text-${name}${suffix}.svg`}
+                            height="17" />;
                 },
             );
 
diff --git a/src/components/views/rooms/MessageComposerInput.js b/src/components/views/rooms/MessageComposerInput.js
index eed6b18aa4a..89e4107a56c 100644
--- a/src/components/views/rooms/MessageComposerInput.js
+++ b/src/components/views/rooms/MessageComposerInput.js
@@ -21,17 +21,14 @@ import type SyntheticKeyboardEvent from 'react/lib/SyntheticKeyboardEvent';
 
 import { Editor } from 'slate-react';
 import { getEventTransfer } from 'slate-react';
-import { Value, Document, Event, Block, Inline, Text, Range, Node } from 'slate';
+import { Value, Document, Block, Inline, Text, Range, Node } from 'slate';
+import type { Change } from 'slate';
 
 import Html from 'slate-html-serializer';
 import Md from 'slate-md-serializer';
 import Plain from 'slate-plain-serializer';
 import PlainWithPillsSerializer from "../../../autocomplete/PlainWithPillsSerializer";
 
-// import {Editor, EditorState, RichUtils, CompositeDecorator, Modifier,
-//     getDefaultKeyBinding, KeyBindingUtil, ContentState, ContentBlock, SelectionState,
-//     Entity} from 'draft-js';
-
 import classNames from 'classnames';
 import Promise from 'bluebird';
 
@@ -54,7 +51,7 @@ import Markdown from '../../../Markdown';
 import ComposerHistoryManager from '../../../ComposerHistoryManager';
 import MessageComposerStore from '../../../stores/MessageComposerStore';
 
-import {MATRIXTO_MD_LINK_PATTERN} from '../../../linkify-matrix';
+import {MATRIXTO_MD_LINK_PATTERN, MATRIXTO_URL_PATTERN} from '../../../linkify-matrix';
 const REGEX_MATRIXTO_MARKDOWN_GLOBAL = new RegExp(MATRIXTO_MD_LINK_PATTERN, 'g');
 
 import {asciiRegexp, unicodeRegexp, shortnameToUnicode, emojioneList, asciiList, mapUnicodeToShort, toShort} from 'emojione';
@@ -118,6 +115,15 @@ function onSendMessageFailed(err, room) {
     });
 }
 
+function rangeEquals(a: Range, b: Range): boolean {
+    return (a.anchorKey === b.anchorKey
+        && a.anchorOffset === b.anchorOffset
+        && a.focusKey === b.focusKey
+        && a.focusOffset === b.focusOffset
+        && a.isFocused === b.isFocused
+        && a.isBackward === b.isBackward);
+}
+
 /*
  * The textInput part of the MessageComposer
  */
@@ -146,28 +152,17 @@ export default class MessageComposerInput extends React.Component {
 
         Analytics.setRichtextMode(isRichTextEnabled);
 
-        this.state = {
-            // whether we're in rich text or markdown mode
-            isRichTextEnabled,
-
-            // the currently displayed editor state (note: this is always what is modified on input)
-            editorState: this.createEditorState(
-                isRichTextEnabled,
-                MessageComposerStore.getEditorState(this.props.room.roomId),
-            ),
-
-            // the original editor state, before we started tabbing through completions
-            originalEditorState: null,
-
-            // the virtual state "above" the history stack, the message currently being composed that
-            // we want to persist whilst browsing history
-            currentlyComposedEditorState: null,
+        this.client = MatrixClientPeg.get();
 
-            // whether there were any completions
-            someCompletions: null,
-        };
+        // track whether we should be trying to show autocomplete suggestions on the current editor
+        // contents. currently it's only suppressed when navigating history to avoid ugly flashes
+        // of unexpected corrections as you navigate.
+        // XXX: should this be in state?
+        this.suppressAutoComplete = false;
 
-        this.client = MatrixClientPeg.get();
+        // track whether we've just pressed an arrowkey left or right in order to skip void nodes.
+        // see https://github.com/ianstormtaylor/slate/issues/762#issuecomment-304855095
+        this.direction = '';
 
         this.plainWithMdPills    = new PlainWithPillsSerializer({ pillFormat: 'md' });
         this.plainWithIdPills    = new PlainWithPillsSerializer({ pillFormat: 'id' });
@@ -176,18 +171,35 @@ export default class MessageComposerInput extends React.Component {
         this.md = new Md({
             rules: [
                 {
+                    // if serialize returns undefined it falls through to the default hardcoded
+                    // serialization rules
                     serialize: (obj, children) => {
-                        if (obj.object === 'inline') {
-                            switch (obj.type) {
-                                case 'pill':
-                                    return `[${ obj.data.get('completion') }](${ obj.data.get('href') })`;
-                                case 'emoji':
-                                    return obj.data.get('emojiUnicode');
-                            }
+                        if (obj.object !== 'inline') return;
+                        switch (obj.type) {
+                            case 'pill':
+                                return `[${ obj.data.get('completion') }](${ obj.data.get('href') })`;
+                            case 'emoji':
+                                return obj.data.get('emojiUnicode');
                         }
-                    }
-                }
-            ]
+                    },
+                }, {
+                    serialize: (obj, children) => {
+                        if (obj.object !== 'mark') return;
+                        // XXX: slate-md-serializer consumes marks other than bold, italic, code, inserted, deleted
+                        switch (obj.type) {
+                            case 'underlined':
+                                return `<u>${ children }</u>`;
+                            case 'deleted':
+                                return `<del>${ children }</del>`;
+                            case 'code':
+                                // XXX: we only ever get given `code` regardless of whether it was inline or block
+                                // XXX: workaround for https://github.com/tommoor/slate-md-serializer/issues/14
+                                // strip single backslashes from children, as they would have been escaped here
+                                return `\`${ children.split('\\').map((v) => v ? v : '\\').join('') }\``;
+                        }
+                    },
+                },
+            ],
         });
 
         this.html = new Html({
@@ -278,20 +290,46 @@ export default class MessageComposerInput extends React.Component {
             ]
         });
 
-        this.suppressAutoComplete = false;
-        this.direction = '';
+        const savedState = MessageComposerStore.getEditorState(this.props.room.roomId);
+        this.state = {
+            // whether we're in rich text or markdown mode
+            isRichTextEnabled,
+
+            // the currently displayed editor state (note: this is always what is modified on input)
+            editorState: this.createEditorState(
+                isRichTextEnabled,
+                savedState ? savedState.editor_state : undefined,
+                savedState ? savedState.rich_text : undefined,
+            ),
+
+            // the original editor state, before we started tabbing through completions
+            originalEditorState: null,
+
+            // the virtual state "above" the history stack, the message currently being composed that
+            // we want to persist whilst browsing history
+            currentlyComposedEditorState: null,
+
+            // whether there were any completions
+            someCompletions: null,
+        };
     }
 
     /*
      * "Does the right thing" to create an Editor value, based on:
      * - whether we've got rich text mode enabled
      * - contentState was passed in
+     * - whether the contentState that was passed in was rich text
      */
-    createEditorState(richText: boolean, editorState: ?Value): Value {
+    createEditorState(wantRichText: boolean, editorState: ?Value, wasRichText: ?boolean): Value {
         if (editorState instanceof Value) {
+            if (wantRichText && !wasRichText) {
+                return this.mdToRichEditorState(editorState);
+            }
+            if (wasRichText && !wantRichText) {
+                return this.richToMdEditorState(editorState);
+            }
             return editorState;
-        }
-        else {
+        } else {
             // ...or create a new one.
             return Plain.deserialize('', { defaultBlock: DEFAULT_NODE });
         }
@@ -299,7 +337,7 @@ export default class MessageComposerInput extends React.Component {
 
     componentDidMount() {
         this.dispatcherRef = dis.register(this.onAction);
-        this.historyManager = new ComposerHistoryManager(this.props.room.roomId);
+        this.historyManager = new ComposerHistoryManager(this.props.room.roomId, 'mx_slate_composer_history_');
     }
 
     componentWillUnmount() {
@@ -342,7 +380,7 @@ export default class MessageComposerInput extends React.Component {
                 // If so, what should be the format, and how do we differentiate it from replies?
 
                 const quote = Block.create('block-quote');
-                if (this.state.isRichTextEnabled) {    
+                if (this.state.isRichTextEnabled) {
                     let change = editorState.change();
                     if (editorState.anchorText.text === '' && editorState.anchorBlock.nodes.size === 1) {
                         // replace the current block rather than split the block
@@ -360,7 +398,6 @@ export default class MessageComposerInput extends React.Component {
                     let fragmentChange = fragment.change();
                     fragmentChange.moveToRangeOf(fragment.document)
                                   .wrapBlock(quote);
-                                  //.setBlocks('block-quote');
 
                     // FIXME: handle pills and use commonmark rather than md-serialize
                     const md = this.md.serialize(fragmentChange.value);
@@ -441,39 +478,37 @@ export default class MessageComposerInput extends React.Component {
         }
     }
 
-    onChange = (change: Change, originalEditorState: value) => {
-
+    onChange = (change: Change, originalEditorState?: Value) => {
         let editorState = change.value;
 
         if (this.direction !== '') {
             const focusedNode = editorState.focusInline || editorState.focusText;
             if (focusedNode.isVoid) {
+                // XXX: does this work in RTL?
+                const edge = this.direction === 'Previous' ? 'End' : 'Start';
                 if (editorState.isCollapsed) {
-                    change = change[`collapseToEndOf${ this.direction }Text`]();
-                }
-                else {
+                    change = change[`collapseTo${ edge }Of${ this.direction }Text`]();
+                } else {
                     const block = this.direction === 'Previous' ? editorState.previousText : editorState.nextText;
                     if (block) {
-                        change = change.moveFocusToEndOf(block)
+                        change = change[`moveFocusTo${ edge }Of`](block);
                     }
                 }
                 editorState = change.value;
             }
         }
 
+        // when selection changes hide the autocomplete
+        if (!rangeEquals(this.state.editorState.selection, editorState.selection)) {
+            this.autocomplete.hide();
+        }
+
         if (!editorState.document.isEmpty) {
             this.onTypingActivity();
         } else {
             this.onFinishedTyping();
         }
 
-        /*
-        // XXX: what was this ever doing?
-        if (!state.hasOwnProperty('originalEditorState')) {
-            state.originalEditorState = null;
-        }
-        */
-
         if (editorState.startText !== null) {
             const text = editorState.startText.text;
             const currentStartOffset = editorState.startOffset;
@@ -501,9 +536,7 @@ export default class MessageComposerInput extends React.Component {
         }
 
         // emojioneify any emoji
-
-        // XXX: is getTextsAsArray a private API?
-        editorState.document.getTextsAsArray().forEach(node => {
+        editorState.document.getTexts().forEach(node => {
             if (node.text !== '' && HtmlUtils.containsEmoji(node.text)) {
                 let match;
                 while ((match = EMOJI_REGEX.exec(node.text)) !== null) {
@@ -535,36 +568,6 @@ export default class MessageComposerInput extends React.Component {
             editorState = change.value;
         }
 
-/*
-        const currentBlock = editorState.getSelection().getStartKey();
-        const currentSelection = editorState.getSelection();
-        const currentStartOffset = editorState.getSelection().getStartOffset();
-
-        const block = editorState.getCurrentContent().getBlockForKey(currentBlock);
-        const text = block.getText();
-
-        const entityBeforeCurrentOffset = block.getEntityAt(currentStartOffset - 1);
-        const entityAtCurrentOffset = block.getEntityAt(currentStartOffset);
-
-        // If the cursor is on the boundary between an entity and a non-entity and the
-        // text before the cursor has whitespace at the end, set the entity state of the
-        // character before the cursor (the whitespace) to null. This allows the user to
-        // stop editing the link.
-        if (entityBeforeCurrentOffset && !entityAtCurrentOffset &&
-            /\s$/.test(text.slice(0, currentStartOffset))) {
-            editorState = RichUtils.toggleLink(
-                editorState,
-                currentSelection.merge({
-                    anchorOffset: currentStartOffset - 1,
-                    focusOffset: currentStartOffset,
-                }),
-                null,
-            );
-            // Reset selection
-            editorState = EditorState.forceSelection(editorState, currentSelection);
-        }
-*/
-
         if (this.props.onInputStateChanged && editorState.blocks.size > 0) {
             let blockType = editorState.blocks.first().type;
             // console.log("onInputStateChanged; current block type is " + blockType + " and marks are " + editorState.activeMarks);
@@ -591,10 +594,10 @@ export default class MessageComposerInput extends React.Component {
         dis.dispatch({
             action: 'editor_state',
             room_id: this.props.room.roomId,
+            rich_text: this.state.isRichTextEnabled,
             editor_state: editorState,
         });
 
-        /* Since a modification was made, set originalEditorState to null, since newState is now our original */
         this.setState({
             editorState,
             originalEditorState: originalEditorState || null
@@ -672,7 +675,7 @@ export default class MessageComposerInput extends React.Component {
 
     hasMark = type => {
         const { editorState } = this.state
-        return editorState.activeMarks.some(mark => mark.type == type)
+        return editorState.activeMarks.some(mark => mark.type === type)
     };
 
     /**
@@ -684,10 +687,10 @@ export default class MessageComposerInput extends React.Component {
 
     hasBlock = type => {
         const { editorState } = this.state
-        return editorState.blocks.some(node => node.type == type)
+        return editorState.blocks.some(node => node.type === type)
     };
 
-    onKeyDown = (ev: Event, change: Change, editor: Editor) => {
+    onKeyDown = (ev: KeyboardEvent, change: Change, editor: Editor) => {
 
         this.suppressAutoComplete = false;
 
@@ -702,6 +705,23 @@ export default class MessageComposerInput extends React.Component {
             this.direction = '';
         }
 
+        switch (ev.keyCode) {
+            case KeyCode.ENTER:
+                return this.handleReturn(ev, change);
+            case KeyCode.BACKSPACE:
+                return this.onBackspace(ev, change);
+            case KeyCode.UP:
+                return this.onVerticalArrow(ev, true);
+            case KeyCode.DOWN:
+                return this.onVerticalArrow(ev, false);
+            case KeyCode.TAB:
+                return this.onTab(ev);
+            case KeyCode.ESCAPE:
+                return this.onEscape(ev);
+            case KeyCode.SPACE:
+                return this.onSpace(ev, change);
+        }
+
         if (isOnlyCtrlOrCmdKeyEvent(ev)) {
             const ctrlCmdCommand = {
                 // C-m => Toggles between rich text and markdown modes
@@ -715,37 +735,36 @@ export default class MessageComposerInput extends React.Component {
             if (ctrlCmdCommand) {
                 return this.handleKeyCommand(ctrlCmdCommand);
             }
-            return;
         }
+    };
 
-        switch (ev.keyCode) {
-            case KeyCode.ENTER:
-                return this.handleReturn(ev, change);
-            case KeyCode.BACKSPACE:
-                return this.onBackspace(ev, change);
-            case KeyCode.UP:
-                return this.onVerticalArrow(ev, true);
-            case KeyCode.DOWN:
-                return this.onVerticalArrow(ev, false);
-            case KeyCode.TAB:
-                return this.onTab(ev);
-            case KeyCode.ESCAPE:
-                return this.onEscape(ev);
-            default:
-                // don't intercept it
-                return;
+    onSpace = (ev: KeyboardEvent, change: Change): Change => {
+        if (ev.metaKey || ev.altKey || ev.shiftKey || ev.ctrlKey) {
+            return;
         }
+
+        // drop a point in history so the user can undo a word
+        // XXX: this seems nasty but adding to history manually seems a no-go
+        ev.preventDefault();
+        return change.setOperationFlag("skip", false).setOperationFlag("merge", false).insertText(ev.key);
     };
 
-    onBackspace = (ev: Event, change: Change): Change => {
-        if (ev.ctrlKey || ev.metaKey || ev.altKey || ev.ctrlKey || ev.shiftKey) {
+    onBackspace = (ev: KeyboardEvent, change: Change): Change => {
+        if (ev.metaKey || ev.altKey || ev.shiftKey) {
             return;
         }
 
+        const { editorState } = this.state;
+
+        // Allow Ctrl/Cmd-Backspace when focus starts at the start of the composer (e.g select-all)
+        // for some reason if slate sees you Ctrl-backspace and your anchorOffset=0 it just resets your focus
+        if (!editorState.isCollapsed && editorState.anchorOffset === 0) {
+            return change.delete();
+        }
+
         if (this.state.isRichTextEnabled) {
             // let backspace exit lists
             const isList = this.hasBlock('list-item');
-            const { editorState } = this.state;
 
             if (isList && editorState.anchorOffset == 0) {
                 change
@@ -805,7 +824,7 @@ export default class MessageComposerInput extends React.Component {
                     // Handle the extra wrapping required for list buttons.
                     const isList = this.hasBlock('list-item');
                     const isType = editorState.blocks.some(block => {
-                        return !!document.getClosest(block.key, parent => parent.type == type);
+                        return !!document.getClosest(block.key, parent => parent.type === type);
                     });
 
                     if (isList && isType) {
@@ -816,7 +835,7 @@ export default class MessageComposerInput extends React.Component {
                     } else if (isList) {
                         change
                             .unwrapBlock(
-                                type == 'bulleted-list' ? 'numbered-list' : 'bulleted-list'
+                                type === 'bulleted-list' ? 'numbered-list' : 'bulleted-list'
                             )
                             .wrapBlock(type);
                     } else {
@@ -986,7 +1005,7 @@ export default class MessageComposerInput extends React.Component {
         let contentHTML;
 
         // only look for commands if the first block contains simple unformatted text
-        // i.e. no pills or rich-text formatting.
+        // i.e. no pills or rich-text formatting and begins with a /.
         let cmd, commandText;
         const firstChild = editorState.document.nodes.get(0);
         const firstGrandChild = firstChild && firstChild.nodes.get(0);
@@ -995,7 +1014,7 @@ export default class MessageComposerInput extends React.Component {
             firstGrandChild.text[0] === '/')
         {
             commandText = this.plainWithIdPills.serialize(editorState);
-            cmd = SlashCommands.processInput(this.props.room.roomId, commandText);
+            cmd = processCommandInput(this.props.room.roomId, commandText);
         }
 
         if (cmd) {
@@ -1067,8 +1086,8 @@ export default class MessageComposerInput extends React.Component {
                 // didn't contain any formatting in the first place...
                 contentText = mdWithPills.toPlaintext();
             } else {
-                // to avoid ugliness clients which can't parse HTML we don't send pills
-                // in the plaintext body.
+                // to avoid ugliness on clients which ignore the HTML body we don't
+                // send pills in the plaintext body.
                 contentText = this.plainWithPlainPills.serialize(editorState);
                 contentHTML = mdWithPills.toHTML();
             }
@@ -1147,42 +1166,19 @@ export default class MessageComposerInput extends React.Component {
 
         // Select history only if we are not currently auto-completing
         if (this.autocomplete.state.completionList.length === 0) {
+            const selection = this.state.editorState.selection;
 
-            // determine whether our cursor is at the top or bottom of the multiline
-            // input box by just looking at the position of the plain old DOM selection.
-            const selection = window.getSelection();
-            const range = selection.getRangeAt(0);
-            const cursorRect = range.getBoundingClientRect();
+            // selection must be collapsed
+            if (!selection.isCollapsed) return;
+            const document = this.state.editorState.document;
 
-            const editorNode = ReactDOM.findDOMNode(this.refs.editor);
-            const editorRect = editorNode.getBoundingClientRect();
-
-            // heuristic to handle tall emoji, pills, etc pushing the cursor away from the top
-            // or bottom of the page.
-            // XXX: is this going to break on large inline images or top-to-bottom scripts?
-            const EDGE_THRESHOLD = 15;
-
-            let navigateHistory = false;
+            // and we must be at the edge of the document (up=start, down=end)
             if (up) {
-                const scrollCorrection = editorNode.scrollTop;
-                const distanceFromTop = cursorRect.top - editorRect.top + scrollCorrection;
-                console.log(`Cursor distance from editor top is ${distanceFromTop}`);
-                if (distanceFromTop < EDGE_THRESHOLD) {
-                    navigateHistory = true;
-                }
-            }
-            else {
-                const scrollCorrection =
-                    editorNode.scrollHeight - editorNode.clientHeight - editorNode.scrollTop;
-                const distanceFromBottom = editorRect.bottom - cursorRect.bottom + scrollCorrection;
-                console.log(`Cursor distance from editor bottom is ${distanceFromBottom}`);
-                if (distanceFromBottom < EDGE_THRESHOLD) {
-                    navigateHistory = true;
-                }
+                if (!selection.isAtStartOf(document)) return;
+            } else {
+                if (!selection.isAtEndOf(document)) return;
             }
 
-            if (!navigateHistory) return;
-
             const selected = this.selectHistory(up);
             if (selected) {
                 // We're selecting history, so prevent the key event from doing anything else
@@ -1232,11 +1228,8 @@ export default class MessageComposerInput extends React.Component {
         // Move selection to the end of the selected history
         const change = editorState.change().collapseToEndOf(editorState.document);
 
-        // XXX: should we be calling this.onChange(change) now?
-        // Answer: yes, if we want it to do any of the fixups on stuff like emoji.
-        // however, this should already have been done and persisted in the history,
-        // so shouldn't be necessary.
-
+        // We don't call this.onChange(change) now, as fixups on stuff like emoji
+        // should already have been done and persisted in the history.
         editorState = change.value;
 
         this.suppressAutoComplete = true;
@@ -1339,6 +1332,8 @@ export default class MessageComposerInput extends React.Component {
                                 .insertText(suffix)
                                 .focus();
         }
+        // for good hygiene, keep editorState updated to track the result of the change
+        // even though we don't do anything subsequently with it
         editorState = change.value;
 
         this.onChange(change, activeEditorState);
@@ -1437,10 +1432,11 @@ export default class MessageComposerInput extends React.Component {
     };
 
     onFormatButtonClicked = (name, e) => {
-        e.preventDefault(); // don't steal focus from the editor!
+        e.preventDefault();
 
         // XXX: horrible evil hack to ensure the editor is focused so the act
         // of focusing it doesn't then cancel the format button being pressed
+        // FIXME: can we just tell handleKeyCommand's change to invoke .focus()?
         if (document.activeElement && document.activeElement.className !== 'mx_MessageComposer_editor') {
             this.refs.editor.focus();
             setTimeout(()=>{
diff --git a/src/i18n/strings/en_EN.json b/src/i18n/strings/en_EN.json
index 486ecdf1142..2da820d7516 100644
--- a/src/i18n/strings/en_EN.json
+++ b/src/i18n/strings/en_EN.json
@@ -406,6 +406,14 @@
     "Invited": "Invited",
     "Filter room members": "Filter room members",
     "%(userName)s (power %(powerLevelNumber)s)": "%(userName)s (power %(powerLevelNumber)s)",
+    "bold": "bold",
+    "italic": "italic",
+    "deleted": "deleted",
+    "underlined": "underlined",
+    "inline-code": "inline-code",
+    "block-quote": "block-quote",
+    "bulleted-list": "bulleted-list",
+    "numbered-list": "numbered-list",
     "Attachment": "Attachment",
     "At this time it is not possible to reply with a file so this will be sent without being a reply.": "At this time it is not possible to reply with a file so this will be sent without being a reply.",
     "Upload Files": "Upload Files",
@@ -430,14 +438,6 @@
     "Command error": "Command error",
     "Unable to reply": "Unable to reply",
     "At this time it is not possible to reply with an emote.": "At this time it is not possible to reply with an emote.",
-    "bold": "bold",
-    "italic": "italic",
-    "strike": "strike",
-    "underline": "underline",
-    "code": "code",
-    "quote": "quote",
-    "bullet": "bullet",
-    "numbullet": "numbullet",
     "Markdown is disabled": "Markdown is disabled",
     "Markdown is enabled": "Markdown is enabled",
     "No pinned messages.": "No pinned messages.",
@@ -772,7 +772,6 @@
     "Room directory": "Room directory",
     "Start chat": "Start chat",
     "And %(count)s more...|other": "And %(count)s more...",
-    "Share Link to User": "Share Link to User",
     "ex. @bob:example.com": "ex. @bob:example.com",
     "Add User": "Add User",
     "Matrix ID": "Matrix ID",
diff --git a/src/stores/MessageComposerStore.js b/src/stores/MessageComposerStore.js
index 0e6c856e1ba..1d37a7c9e5f 100644
--- a/src/stores/MessageComposerStore.js
+++ b/src/stores/MessageComposerStore.js
@@ -1,5 +1,5 @@
 /*
-Copyright 2017 Vector Creations Ltd
+Copyright 2017, 2018 Vector Creations Ltd
 
 Licensed under the Apache License, Version 2.0 (the "License");
 you may not use this file except in compliance with the License.
@@ -15,6 +15,7 @@ limitations under the License.
 */
 import dis from '../dispatcher';
 import { Store } from 'flux/utils';
+import { Value } from 'slate';
 
 const INITIAL_STATE = {
     // a map of room_id to rich text editor composer state
@@ -54,7 +55,10 @@ class MessageComposerStore extends Store {
 
     _editorState(payload) {
         const editorStateMap = this._state.editorStateMap;
-        editorStateMap[payload.room_id] = payload.editor_state;
+        editorStateMap[payload.room_id] = {
+            editor_state: payload.editor_state,
+            rich_text: payload.rich_text,
+        };
         localStorage.setItem('editor_state', JSON.stringify(editorStateMap));
         this._setState({
             editorStateMap: editorStateMap,
@@ -62,7 +66,15 @@ class MessageComposerStore extends Store {
     }
 
     getEditorState(roomId) {
-        return this._state.editorStateMap[roomId];
+        const editorStateMap = this._state.editorStateMap;
+        // const entry = this._state.editorStateMap[roomId];
+        if (editorStateMap[roomId] && !Value.isValue(editorStateMap[roomId].editor_state)) {
+            // rehydrate lazily to prevent massive churn at launch and cache it
+            editorStateMap[roomId].editor_state = Value.fromJSON(editorStateMap[roomId].editor_state);
+        }
+        // explicitly don't setState here because the value didn't actually change, we just hydrated it,
+        // if a listener received an update they too would call this method and have a hydrated Value
+        return editorStateMap[roomId];
     }
 
     reset() {
diff --git a/test/components/views/rooms/MessageComposerInput-test.js b/test/components/views/rooms/MessageComposerInput-test.js
index 708071df23c..662fbc7104b 100644
--- a/test/components/views/rooms/MessageComposerInput-test.js
+++ b/test/components/views/rooms/MessageComposerInput-test.js
@@ -10,7 +10,6 @@ const MessageComposerInput = sdk.getComponent('views.rooms.MessageComposerInput'
 import MatrixClientPeg from '../../../../src/MatrixClientPeg';
 import RoomMember from 'matrix-js-sdk';
 
-/*
 function addTextToDraft(text) {
     const components = document.getElementsByClassName('public-DraftEditor-content');
     if (components && components.length) {
@@ -21,7 +20,9 @@ function addTextToDraft(text) {
     }
 }
 
-describe('MessageComposerInput', () => {
+// FIXME: These tests need to be updated from Draft to Slate.
+
+xdescribe('MessageComposerInput', () => {
     let parentDiv = null,
         sandbox = null,
         client = null,
@@ -300,5 +301,4 @@ describe('MessageComposerInput', () => {
         expect(spy.args[0][1].body).toEqual('[Click here](https://some.lovely.url)');
         expect(spy.args[0][1].formatted_body).toEqual('<a href="https://some.lovely.url">Click here</a>');
     });
-});
-*/
\ No newline at end of file
+});
\ No newline at end of file