i3 Window manager?: When opening preferences, the entire screen flickers

[luca-ing]

Observation: When I open Projecteur preferences,

• the entire screen flickers like mad (between, it seems, black and the actual screeen image).
• I can apparently only interact with the window while the screen isn't black. So I need to click everything many times, until I hit the right timing by luck (e.g. to close the window again)
• Once I close the window, the flickering stops

Expectation: Opening the window should not produce any visual distortion, interaction with the window should be as usual

Steps to reproduce:

• Start Projecteur 0.4-alpha.9
• open the settings window
• always reproducible

Environment:

• compiled using qt 5.12.2
• using i3 window manager

• environment:

  
  $ uname -a
  Linux dell 4.18.0-16-generic #17-Ubuntu SMP Fri Feb 8 00:06:57 UTC 2019 x86_64 x86_64 x86_64 GNU/Linux
  
  $ lsb_release -a
  No LSB modules are available.
  Distributor ID: Ubuntu
  Description:    Ubuntu 18.10
  Release:    18.10
  Codename:   cosmic

$ i3 --version i3 version 4.15 (2018-03-10) © 2009 Michael Stapelberg and contributors

[jahnf]

@luca-ing : Could you please retry with the lastest version from develop - especially with the preferences screen a lot changes since the version you reported the issue with. Thanks in advance.

For that matter, every feedback for projecteur + i3 window manager from anybody is appreciated.

[luca-ing]

In today's develop, I confirm the flickering is gone.

Thanks, @jahnf . I appreciate the work you put into this.