Make the media preview window movable

[qtlis]

#683 was closed because the issue was probably caused by the window manager. Still, it would be nice if this could at least be worked around by being able to move the media preview window:

• Don't close the media preview window when a modifier key is pressed. Many WMs allow dragging a window by grabbing it anywhere while holding a modifier key (usually Alt or Meta).
• Maybe make the window draggable on its own, without any modifier keys.
• Remember the position of the window so it only needs to be moved to the right place once

[Vistaus]

Maybe make the window draggable on its own, without any modifier keys.

I believe this is possible with GTK4 now (correct me if I'm wrong!).

[baedert]

Would be possible in gtk3 as well as far as I know, the window is just modal so sticks to the parent window in gnome. I also just wanted it to be a quick way to look at an image, not a full blown window, that's why it doesn't have any window decoration at all.

[Vistaus]

Ah, I see. Didn't know that. Thanks for the explanation :)