Workaround:
<telerik:RadTabStrip ID="RadTabStrip1" runat="server" MultiPageID="RadMultiPage1">
	<Tabs>
		<telerik:RadTab Text="tab1" Selected="true"></telerik:RadTab>
		<telerik:RadTab Text="tab2"></telerik:RadTab>
	</Tabs>
</telerik:RadTabStrip>
<telerik:RadMultiPage ID="RadMultiPage1" runat="server">
	<telerik:RadPageView ID="RadPageView1" runat="server" Selected="true">RadPageView 1</telerik:RadPageView>
	<telerik:RadPageView ID="RadPageView2" runat="server">
		<telerik:RadEditor ID="RadEditor1" runat="server" EnableTrackChanges="true"
			TrackChangesSettings-CanAcceptTrackChanges="true" ToolsFile="ToolsTrackChanges.xml">
			<Content>
				<p>paragraph 1</p>
				<p>paragraph 2</p>
			</Content>
		</telerik:RadEditor>

	</telerik:RadPageView>
</telerik:RadMultiPage>

<script type="text/javascript">
	$telerik.$.extend(Telerik.Web.UI.RadEditor.prototype, {
		_initEvents: function() {
			var editor = this;
			if (editor.__original__initEvents) {
				editor.__original__initEvents();
			}
			editor.add_domChange(Function.createDelegate(editor, editor._domChangedHandler));
			editor.attachInternalHandler("keypress", Function.createDelegate(editor, editor._keyPressHandler));
			editor.attachInternalHandler("keydown", Function.createDelegate(editor, editor._keyDownHandlerEnableTrackChangesOverride));
			editor.attachInternalHandler("keydown", Function.createDelegate(editor, editor._keyDownHandler));
		}
	});
</script>