Created attachment 188464 [details] Calibre with default theme, drag handle visible SUMMARY When using CALIBRE_USE_SYSTEM_THEME=1, Calibre will use the system QT theme. There are no visual issues and it does look very great, however, the left and right panels docked inside the application cannot be resized. Using any other QT theme allows to resize them. It seems like the resize handles either disappear or get a width of 0 pixels with Breeze, which is odd. STEPS TO REPRODUCE 1. Launch Calibre with CALIBRE_USE_SYSTEM_THEME=1 calibre 2. Try resizing the side panels OBSERVED RESULT Unable to resize the side panels. There are no handles visible and the cursor does not change to a double horizontal arrow when hovering over the vertical separator. EXPECTED RESULT There should be a drag handle indicating the panel is resizable, and the panel should resize when dragged. SOFTWARE/OS VERSIONS Operating System: CachyOS Linux KDE Plasma Version: 6.5.4 KDE Frameworks Version: 6.22.0 Qt Version: 6.10.1 Kernel Version: 6.18.3-2-cachyos (64-bit) Graphics Platform: Wayland Processors: 12 × Intel® Core™ i7-9750H CPU @ 2.60GHz Memory: 16 GiB of RAM (15.5 GiB usable) Graphics Processor 1: Intel® UHD Graphics 630 Graphics Processor 2: NVIDIA GeForce GTX 1660 Ti ADDITIONAL INFORMATION I have reported the issue on the side of Calibre, but they said they will not investigate it as they do not officially support system themes.
Created attachment 188465 [details] Calibre with Breeze theme, drag handle missing
In breeze, the handles are intentionally invisible. You should be able to resize the sidebar from its line, though. If you can't, that's a Calibre bug.
Still cannot be resized with the separator. Definitely a Calibre bug, indeed. Sadly they won't fix it.