Fix display of screen refresh rate in kcontrol/tderandrtray (bug TDE/tde-75) #250

A fix/workaround for TDE/tde#75
I believe a proper solution would be to fix the bug in nvidia driver, but due to lack control over it we will have to settle to this workaround.

I'm pretty sure that it should work fine, but unfortunately it's hard to test properly on my configuration. To test:

install tdelibs with patches
run tdecmshell rand
scroll through combinations of screen sizes and refresh rates and verify that:
- there are no extra unsupported resolutions/refresh rates
- compare those against output of xrandr
- try to change refresh rate (if you have several options available)

I'm interested in results for both nvidia and some FOSS drivers.

PS: the PR contains a second small patch regards serialization of screen reflection.

I can't reproduce the issue, so I have asked Q4OS team to test the fix (see https://www.q4os.org/forum/viewtopic.php?id=3939)

EDIT: for info, no side effects noticed on y msystem with the patch installed.

@MicheleC, please check if it at least doesn't break things... TBH, I'm a bit more worried about that...

@MicheleC, please check if it at least doesn't break things... TBH, I'm a bit more worried about that...

Yes, that is what I meant by "no side effects" in my previous (edited) comment. The available resolutions and refresh rates are the same with and without patches in my virtualbox machine.
Testing on real hardware gave me some issues even without the patch. Running Q4OS live from a USB stick, the "Display" module works fine on my Thinkpad, but when I use the "Monitor & Display" module I see long delays to open the config dialg. Enabling global display control and clicking "Apply" messed up the colors of the screen and even reverting that didn't work well. So probably some other issues there.

I suggest we wait for the test from Q4OS first. If successful, we can build PSB/PTB packages with the patch and ask for some additional testing to some users. If no side effect observed for a while, then we can officially merge the patch.
What do you think about that?

Yes, that is what I meant by "no side effects"

I had typed the message before saw the edit..

Enabling global display control and clicking "Apply" messed up the colors of the screen and even reverting that didn't work well

Have seen that too but couldn't reliably reproduce it... had to restart X server...

What do you think?

Yep, sounds good

Have seen that too but couldn't reliably reproduce it... had to restart X server..

Seems to happen all the times here. Need to logout (reboot not strictly required here) to get the colors back as they should. Probably worth a different issue report.

For reference, issue TDE/tde#154 create to report the problem with the "Monitor & Display" module.