Upgrade to CKEditor 4.3.4 released on March 24 2014.
Changelog since 4.3.1:
#11597: [IE11] Fixed: Error thrown when trying to open the preview using the keyboard.
#11544: Placeholders will no longer be upcasted in parents not accepting <span> elements.
#8663: Fixed element.renameNode() not clearing the element.getName() cache.
#11574: Fixed: Backspace destroying the DOM structure if an inline editable is placed in a list item.
#11603: Fixed: Table Resize attaches to tables outside the editable.
#9205, #7805, #8216: Fixed:
appearing in data in various cases where HTML comments are placed next to " or '.
#11635: Fixed: Some attributes are not protected before the content is passed through the fix bin.
#11660: [IE] Fixed: Table content is lost when some extra markup is inside the table.
#11641: Fixed: Switching between modes in the classic editor removes content styles for the inline editor.
#11568: Fixed: Styles drop-down list is not enabled on selection change.
#11500: [Webkit/Blink] Fixed: Selection lost when setting data in another inline editor. Additionally, selection.removeAllRanges() is now scoped to selection's root.
#11104: [IE] Fixed: Various issues with scrolling and selection when focusing widgets.
#11487: Moving mouse over the Enhanced Image widget will no longer change the value returned by the editor.checkDirty() method.
#8673: [WebKit] Fixed: Cannot select and remove the Page Break.
#11413: Fixed: Incorrect editor.execCommand() behavior.
#11438: Splitting table cells vertically is no longer changing table structure.
#8899: Fixed: Links in the About CKEditor dialog window now open in a new browser window or tab.
#11490: Fixed: Menu button panel not showing in the source mode.
#11417: The widget.doubleclick event is not canceled anymore after editing was triggered.
#11253: [IE] Fixed: Clipped upload button in the Enhanced Image dialog window.
#11359: Standardized the way anchors are discovered by the Link plugin.
#11058: [IE8] Fixed: Error when deleting a table row.
#11508: Fixed: htmlDataProcessor discovering protected attributes within other attributes' values.
#11533: Widgets: Avoid recurring upcasts if the DOM structure was modified during an upcast.
#11400: Fixed: The domObject.removeAllListeners() method does not remove custom listeners completely.
#11493: Fixed: The selection.getRanges() method does not override cached ranges when used with the onlyEditables argument.
#11390: [IE] All XML plugin methods now work in IE10+.
#11542: [IE11] Fixed: Blurry toolbar icons when Right-to-Left UI language is set.
#11504: Fixed: When config.fullPage is set to true, entities are not encoded in editor output.
#11004: Integrated Enhanced Image dialog window with Advanced Content Filter.
#11439: Fixed: Properties get cloned in the Cell Properties dialog window if multiple cells are selected.
#11331: A menu button will have a changed label when selected instead of using the aria-pressed attribute.
#11177: Widget drag handler improvements:
#11176: Fixed: Initial position is not updated when the widget data object is empty.
#11001: Fixed: Multiple synchronous layout recalculations are caused by initial drag handler positioning causing performance issues.
#11161: Fixed: Drag handler is not repositioned in various situations.
#11281: Fixed: Drag handler and mask are duplicated after widget reinitialization.
#11207: [Firefox] Fixed: Misplaced Enhanced Image resizer in the inline editor.
#11102: CKEDITOR.template improvements:
#11102: Added newline character support.
#11216: Added "\'" substring support.
#11121: [Firefox] Fixed: High Contrast mode is enabled when the editor is loaded in a hidden iframe.
#11350: The default value of config.contentsCss is affected by CKEDITOR.getUrl.
#11097: Improved the Autogrow plugin performance when dealing with very big tables.
#11290: Removed redundant code in the Source Dialog plugin.
#11133: Page Break becomes editable if pasted.
#11126: Fixed: Native Undo executed once the bottom of the snapshot stack is reached.
#11131: Div Editing Area: Fixed: Error thrown when switching to source mode if the selection was in widget's nested editable.
#11139: Div Editing Area: Fixed: Elements Path is not cleared after switching to source mode.
#10778: Fixed a bug with range enlargement. The range no longer expands to visible whitespace.
#11146: [IE] Fixed: Preview window switches Internet Explorer to Quirks Mode.
#11186: Introduced the widgets.repository.addUpcastCallback method that allows to block upcasting given element to a widget.
#11307: Fixed: Paste as Plain Text conflict with the MooTools library.
#11140: [IE11] Fixed: Anchors are not draggable.
#11379: Changed default contents line-height to unitless values to avoid huge text overlapping (like in #9696).
#10787: [Firefox] Fixed: Broken replacement of text while pasting into div-based editor.
#10884: Widgets integration with the Show Blocks plugin.
#11021: Fixed: An error thrown when selecting entire editable contents while fake selection is on.
#11086: [IE8] Re-enable inline widgets drag&drop in Internet Explorer 8.
#11372: Widgets: Special characters encoded twice in nested editables.
#10068: Fixed: Support for protocol-relative URLs.
#11283: Enhanced Image: A <div> element with text-align: center and an image inside is not recognised correctly.
#11196: Accessibility Instructions: Allowed additional keyboard button labels to be translated in the dialog window.