I have been facing this issue from last week.
It's been 1 year using Zorin as my only primary distro and never had this issue before but now every time I open Thunar, it's side pane is flickering.
It's working fine (not flickering) when the sidepane is disabled but everytime I enable the side pane it consistently keeps flickering. If I don't close the window while it flickering then my keyboard and systray icons become unresponsive.
Solutions I tried:
1- reinstalled Thunar (didn't fix the issue)
2- reset to default themes (didn't fix the issue)
3- reboot system (didn't fix the issue)
There are no flickerings when Thunar is in sudo mode. But I don't want to use it in sudo everytime.
When I Launch Thunar from terminal it opens Thunar and immediately exits the process but Thunar window stays active and terminal is not generating any error issues while flickering
So I thought using a different file manager so I installed Nautilus but same issue is happening
here, the side pane started flickering. This time the terminal generated some errors
It sounds like a configuration file may be corrupted.
You might try the following. Warning: This will result your custom configurations to defaults.
mv ~/.config ~/.config-bk
Log out and back in and test.
IF Thunar is working correctly, you might want to go into !/.config-bk and move your ~/.config-bk/xfce4/panel/ contents to ~/.config/xfce4/panel/ so that you do not need to manually reconfigure all your panel settings and items.
EDIT
I just did a couple tests...
The Keyboard Shortcut for show/hide the File Manager Treeview is F9 key.
I launched Thunar and Nautilus (individually) and held down the F9 key and recreated a similar flicker.
You might check either the keyboard shortcut or check your F9 Key on your keyboard and see if it is gummed up and sticking.
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