Multimedia keys not working while xfce-panel in use. Any Solution?

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http://askubuntu.com – I am using XFCE 4.10. Whenever xfce-Panel is in particular use say any menu open from xfce-panel, either right click menu or application menu. Volume control and all other multimedia(play/pause,stop,prev,next, and volume control) keys stop working. As soon as click on desktop they start work again. Any Solution?? (HowTos)