Wrong positioning dialog windows on linux

[gucio321]

Describe the bug
sometimes, when a dialog's error message should be opened, its window is placed in a wrong position of the screen.

To Reproduce
Steps to reproduce the behavior:

1. Open MPQ editor
2. navigate to d2data.mpq/data/global
3. try to open chars_cof.mpq (this file is bugged, so editor shouldn't be created)
4. error message will be displayed, but in wrong place of screen (see screenshot)

Expected behavior
dialog should be opened in a screen's center

Screenshots

Desktop (please complete the following information):

• OS: Fedora release 33 (Thirty Three)
  it might also depend on desktop:
• desktop: GNOME Shell 3.38.3

[gucio321]

we can also see, that the error message isn't focused by default.

[gravestench]

Is there some place where you're telling giu/imgui to open the dialog in the center and to have focus...? Even if so, wouldn't this actually just be a bug of giu/imgui...?

[gucio321]

it isn't giu / imgui issue. Thats dialog's fault.

[gravestench]

That's good; it isn't an issue with hellspawner.