Gnome 3 ALT+Mouse window moving disabled?

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https://bbs.archlinux.org – Since when is the alt+mouse shortcut for moving windows disabled?I'm using gnome 3 on my thinkpad and sometimes windows are just too big so that I have to drag them behind the gnome shell's panel.I used to do thaat with holding down alt and the left mouse button.But somehow this shortcut doesn't exist anymore in my system and I don't know how to get it back.In the gnomes shortcut manager I found out that I now can do that with alt+f7 which isn't quite good since I also have to press the Notebooks Fn-Key and sadly I can't overwrite this shortcut with alt+left mouse (HowTos)