Created attachment 176333 [details] screecast - cannot set panel width in Plasma 6.2.4 SUMMARY Nothing happens when you try to change a panel's width when it' set to custom width. TO REPRODUCE 1. Create a new panel 2. Open edit mode 3. Set the width to custom 4. Try to drag the slider(?) SYSTEM INFO Operating System: openSUSE Tumbleweed 20241202 KDE Plasma Version: 6.2.4 KDE Frameworks Version: 6.8.0 Qt Version: 6.8.0 Kernel Version: 6.11.8-1-default (64-bit) Graphics Platform: Wayland Processors: 16 × 13th Gen Intel® Core™ i7-13620H Graphics Processor: Mesa Intel® Graphics Manufacturer: SLIMBOOK
That central 'slider' is for adjusting the horizontal position of a panel when it's not full width, a tool-tip would say that if it was enabled; so you first have to reduce the width of the panel by dragging either the left or right end of the white bar. There should be small arrows at either end of the white bar indicating the panel ends, but they aren't visible in your screencast, so that's probably a separate bug.
See bug #496907 *** This bug has been marked as a duplicate of bug 496907 ***