Fix #494: make Keyboard more resilient against structure resets

CHANGES.md

@@ -62,6 +62,8 @@ This document outlines changes since 0.3.0.  For older changelogs, see the
   appropriately if the footer node is present. (#463)
 * The `CellSelection` mixin now properly deselects if an unselected cell within
   the same row as a selected cell is right-clicked.
+* Fixed issues with the `Keyboard` mixin pertaining to resetting columns, or
+  not setting them initially. (#494)
 * The `Keyboard` mixin now ensures that if the header area is scrolled due to a
   focus shift, the body scrolls with it. (#474)
 

Keyboard.js

@@ -79,10 +79,17 @@ var Keyboard = declare(null, {
 				isHeader = areaNode === grid.headerNode,
 				initialNode = areaNode;
 
-			if(isHeader){
+			function initHeader(){
 				grid._focusedHeaderNode = initialNode =
 					cellNavigation ? grid.headerNode.getElementsByTagName("th")[0] : grid.headerNode;
-				initialNode.tabIndex = grid.tabIndex;
+				if(initialNode){ initialNode.tabIndex = grid.tabIndex; }
+			}
+
+			if(isHeader){
+				// Initialize header now (since it's already been rendered),
+				// and aspect after future renderHeader calls to reset focus.
+				initHeader();
+				aspect.after(grid, "renderHeader", initHeader, true);
 			}else{
 				aspect.after(grid, "renderArray", function(ret){
 					// summary:

test/Keyboard.html

@@ -92,6 +92,8 @@ <h3>Buttons to test programmatic focus</h3>
 			</div>
 			<div>Focus header (no argument):
 				<button onclick="grid.focusHeader();">Cell-navigation Grid</button>
+				<button onclick="grid.set('columns', grid.columns); grid.focusHeader();">
+					Reset columns, then focus</button>
 			</div>
 		</div>
 	</body>