Such functionality would improve the user experience for UI interaction of the end-users with the RadEditor tools.

Such behavior can be achieved using the following customization with the RadEditor control:

<telerik:RadEditor ID="RadEditor1" runat="server" OnClientLoad="OnClientLoad">
</telerik:RadEditor>
<script>
    function OnClientLoad(editor, args) {
        editor.attachEventHandler("onkeyup", function (e) {
            if (e.keyCode == 27)
            {
                closeContextMenus(editor.get_toolAdapter()._contextMenus);
            }
        })
    }

    function closeContextMenus(contextMenus) {
        for (var menu in contextMenus) {
            contextMenus[menu].hide();
        }
    }
</script>