Bug#751075: marco: hard to resize certain windows (e.g. devhelp)

[Vlad Orlov]

reassign 751075 libgtk-3-0
forcemerge 744249 751075
thanks

> If you start something like Devhelp, and move the mouse cursor to its
> window borders, the resize cursor will appear as normal. But if you then
> press the mouse button to try to drag that border, the window menu will
> appear instead.

Devhelp 3.12 uses CSD (client-side decorations), so this is exactly
the same as [1].

[1] https://bugs.debian.org/744249