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Author Topic: Window flickering on Ubuntu 24.04 in Lazarus 3.8  (Read 651 times)

dvhx

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Window flickering on Ubuntu 24.04 in Lazarus 3.8
« on: April 07, 2025, 04:58:44 pm »
I upgraded from Ubuntu 22.04 to Ubuntu 24.04 (it was clean install on new SSD drive). I'm using JWM window manager. When I run any app made in lazarus (including lazarus itself) there is weird flickering of the window. Sometimes the app doesn't start until I alt+tab twice. I thought it was disto's lazarus issue so I uninstalled it and installed Lazarus 3.8 (rev Unknown) FPC 3.2.2 x86_64-linux-gtk2 from sourceforge. The issue ramains, I tried older JWM (from 22.04 where it worked) but that didn't help. I tried openbox wm it's doing it there as well. I tried few other WM and in some it is worse, for example in miwm the window just slowly flows up in a flickering manner. It's relatively ok for empty window but as I add components (main menu, memo alClient) it gets progressively worse. If I change window left/top/width/height in FormCreate the flickering is worse, sometimes it never stops (until double Alt+Tab). The lazarus itself is doing it too. I tried sleep(100) and application.processMessages in random places but it didn't help.

This is what it looks like in JWM: https://www.youtube.com/watch?v=qo7U9hzwyeo
This is what it looks like in MIWM: https://www.youtube.com/watch?v=gBWfno9rE9M

It seems like some kind of discrepancy between WM's desired window size and Lazarus desired window size and they fighting each other.

TRon

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Re: Window flickering on Ubuntu 24.04 in Lazarus 3.8
« Reply #1 on: April 07, 2025, 06:08:37 pm »
The question that should be answered is what display server is being used.
Today is tomorrow's yesterday.

dvhx

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Re: Window flickering on Ubuntu 24.04 in Lazarus 3.8
« Reply #2 on: April 07, 2025, 09:15:07 pm »
Xorg

TRon

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Re: Window flickering on Ubuntu 24.04 in Lazarus 3.8
« Reply #3 on: April 08, 2025, 02:02:32 am »
In case being sure that ubuntu is not using wayland (which is the default) then you could try the latest release candidate of Lazarus (4.0RC3) and see if that improves the situation.

Other than that, sorry to say, no idea.
Today is tomorrow's yesterday.

dvhx

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Re: Window flickering on Ubuntu 24.04 in Lazarus 3.8
« Reply #4 on: April 08, 2025, 11:07:11 am »
These are only my apps so for now I used BorderStyle = bsSingle and I'll wait for 4.0

 

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