windows shouldn't change size when moving them (and certainly not just grabbing them)

Submitted by RJVB

Assigned to Olivier Fourdan @olivier

Link to original bug (#13209)

Description

I work with multi-head set-ups and have grown accustomed to sizing windows vertically so they take up the whole available height via a keyboard shortcut. I don't mind toggling that state back off manually before dragging a window to a different screen, because that's a relatively rare event.

Somewhere after 4.11.2 a change must have been introduced that causes a side-effect I find very annoying: windows lose the vertical-maximised state as soon as you grab their titlebar. With v4.11.2 build I could move such windows around as I liked without having to resize the window again afterwards (horizontally but really it should be my choice if I want to move part of a window off-screen). It's not just that I have to hit the shortcut key again, the (potential) effects on window content, forced redrawing cycles etc. are not really acceptable to me either.

I'd appreciate a pointer to the relevant changes in the code or if possible even a commit to reverse, that's more important to me than getting this reverted officially (though I'd be happy to help work out a solution that works for everyone).