xbmc/xbmc — comment on commit 2b244631773c1503783fc187115c70023d7d0e7a
File: addons/skin.confluence/720p/DialogButtonMenu.xml line 204
By ScudLee:

Because the background bottom image has id="10" also, I think this prevents you from going "up" from the exit button at the top to whatever button is at the bottom (when you have mouse input disabled).