Created attachment 112941 [details] mouse-corner My panel is at the bottom of the screen, and the kickoff menu icon is placed on the left-most corner. If mouse cursor is at the bottom-left corner, I could not activate the menu. In the screenshot (mouse-corner), the white area is just for showing the mouse cursor, the read lines are screen's border.
This issue I experienced since v5.11, others also have this too: https://www.reddit.com/r/kde/comments/6suvg4/kde_plasma_5_dead_space_on_bottom_left_of_kickoff/?st=jhr859h5&sh=a0af565c If I resizing the panel, then it has (random) gap/space between the panel and the usable desktop space. In the screenshots, I set the background in red, the screenshots are numbered 1, 2, 3, corresponded with descriptions: 1) Right after I start resizing the panel 2) Place the panel on the top, the gap **randomly** changes its position. 3) After number of moves, place the panel again on the top, now the gap changes. After several attempts, the gap disappears, I place the panel on the bottom again, and now the kickoff menu can be activate like normal. But if I restart the PC, the problem appears again.
Created attachment 112942 [details] 1
Created attachment 112943 [details] 2
Created attachment 112944 [details] 3
I was able to reproduce this on a clean install : 1.) Disable compositing (e.g. by pressing Alt+Shift+F12) 2.) Move the panel to the left screen edge -> Notice that there's already some space at the bottom of the panel 3.) Move the panel to the top screen edge -> Notice that there's now a space between the panel itself and the area where the width could be changed 4.) Move the panel back to the bottom screen edge -> There's now a couple of pixels on the screen bottom without a panel. As soon as you turn compositing back on, it looks good again and works as expected. If you turn off compositing again, the issue reported is visible and in effect. My guess (without looking at the source): when compositing is off, there's still some "shadow" margin or padding calculated for "left panel" (probably also "right panel") and "top panel" which will persist even after moving back to the "bottom panel".
*** This bug has been marked as a duplicate of bug 387775 ***
I think this is a different issue than bug 387775 though. In that bug, the problem is the screen edges and screen corners. In this case, the problem is from "shadows" that are still applied even though compositing is turned off thus actually leaving gaps and visual glitches in the panel. See esp. attachment 112943 [details] - the red rectangle should not be visible right of the panel.
This seems to be fixed, might be thanks to https://phabricator.kde.org/R242:412a517576d5505c9f700f13b8f33257c07e220d (see also https://bugs.kde.org/show_bug.cgi?id=389215 )