Eyedropper outside app by key command

Hi guys,

i know that its working to use the eyedropper outside the app already,

but what i dont understand is that its only possible when clicking first on the foreground/background color picker widget in the left bottom corner.

Could you also add this to they key commands, e.g. by pressing alt + going outside the app.
I think this should be fast to implement, and makes the work process much more agile.