Dear Stefan,
Thank you for reporting the bug.
You could have submitted the bug via https://bugreport.java.com/bugreport/
Anyway, I reproduced the issue and now I've submitted the bug for you:
https://bugs.openjdk.java.net/browse/JDK-8280482
"Window transparency bug on Linux Mint"
I attached a modified version of your testcase which creates all the
windows on the EDT.
Even though I see the problem, there could be something wrong with the
test, or possibly window placement. If I add a delay after a window is
created, I can see that all the screen is getting covered gradually with
windows and all the windows have the same level of translucency. When
the bottom of the screen is reached, the new windows get moved above so
that the newly created window does not cover the taskbar. This creates a
darker rectangle seen along the bottom of the screen on the main monitor.
In my environment, the dark square area that you have on your screenshot
is not as large, it covers only the part of the screen on the main
monitor. At the same time, this area appears only when all the windows
are created. Again, it could be that some of the windows of the grid get
misplaced for whatever reason. Perhaps, the calculation of the grid has
an error or something like that.
Eventually, it may be a bug not in Java but in the sample app. I'll play
around with it over the weekend if I have time.
On 21/01/2022 20:10, Stefan Reich wrote:
Dear Sirs or Madams,
I make a visual recognition tool <https://gaz.ai> in Java that would
tremendously benefit from the ability to show translucent windows. Indeed,
Java has such an ability but it is broken on my Linux Mint 19 ThinkPad for
unknown reasons (screenshot <https://botcompany.de/images/1103064>).
All the details are here:
https://github.com/adoptium/adoptium-support/issues/430
I'd love to see this fixed. Not sure how reproducible it is or if there is
anything screwed in my Linux Mint installation. Seems to run fine otherwise
though.
Many greetings,
Stefan Reich
--
Regards,
Alexey
