[Bf-taskforce25] Mouse Focus on Button Zoom

[Christopher Cherrett]

I just tried out the zoom of the buttons window in 2.5. It is very nice 
but I think it might be even more useful if when you zoomed in with the 
mouse scroll wheel that the mouse cursor became the focused area of the 
zoom.

This way you can very easily move your mouse to the area you want to 
see, zoom in and you are there.

Thanks!