Fix pasting multiline code in single-lined text area (#1348)

When pasting multiline code in a single-lined text area, only the first line will be inserted.

CHANGELOG.md

@@ -40,9 +40,12 @@
 - [Disable area selection][1318]. The area selection was visible despite being
   non-functional. To avoid confusion, area selection has been disabled until it
   is [correctly implemented][479].
-- [Handle syntax errors in custom-defined visualizations][#1341]. The IDE is now
+- [Handle syntax errors in custom-defined visualizations][1341]. The IDE is now
   able to run properly, even if some of the custom-defined visualisations inside
   a project contain syntax errors.
+- [Fix issues with pasting multi-line text into single-line text fields][1348].
+  The first copied line will be inserted and all additional lines will be
+  ignored.
 - [Users can opt out of anonymous data gathering.][1328] This can be done with
   the `--no-data-gathering` command-line flag during the startup of the IDE.
 - [You can now start the IDE service without window again.][1353] The command
@@ -66,6 +69,9 @@ you can find their release notes
 [1064]: https://github.com/enso-org/ide/pull/1064
 [1316]: https://github.com/enso-org/ide/pull/1316
 [1318]: https://github.com/enso-org/ide/pull/1318
+[1328]: https://github.com/enso-org/ide/pull/1328
+[1341]: https://github.com/enso-org/ide/pull/1341
+[1348]: https://github.com/enso-org/ide/pull/1348
 [1353]: https://github.com/enso-org/ide/pull/1353
 
 <br/>

src/rust/ensogl/lib/text/src/component/area.rs

@@ -569,7 +569,7 @@ impl Area {
             eval_ sels_cut (m.buffer.frp.delete_left());
 
             eval_ input.paste (m.paste());
-            eval input.paste_string ((s) m.buffer.frp.paste(m.decode_paste(s)));
+            eval input.paste_string((s) m.paste_string(s));
 
 
             eval_ m.buffer.frp.text_change (m.redraw(true));
@@ -954,10 +954,30 @@ impl AreaModel {
         clipboard::read_text(move |t| paste_string.emit(t));
     }
 
+    /// Paste new text in the place of current selections / cursors. In case of pasting multiple
+    /// chunks (e.g. after copying multiple selections), the chunks will be pasted into subsequent
+    /// selections. In case there are more chunks than selections, end chunks will be dropped. In
+    /// case there is more selections than chunks, end selections will be replaced with empty
+    /// strings. I `self.single_line` is set to true then each chunk will be truncated to its first
+    /// line.
+    fn paste_string(&self, s: &str) {
+        let mut chunks = self.decode_paste(s);
+        if self.single_line.get() {
+            for f in &mut chunks {
+                Self::drop_all_but_first_line(f);
+            }
+        }
+        self.buffer.frp.paste(chunks);
+    }
+
     fn decode_paste(&self, encoded:&str) -> Vec<String> {
         encoded.split(RECORD_SEPARATOR).map(|s|s.into()).collect()
     }
 
+    fn drop_all_but_first_line(s: &mut String) {
+        *s = s.lines().nth(0).unwrap_or("").to_string();
+    }
+
     fn key_to_string(&self, key:&Key) -> Option<String> {
         match key {
             Key::Character(s) => Some(s.clone()),