Created attachment 119116 [details] video of problem Version 18.04.3 Operating System: Kubuntu 18.10 KDE Plasma Version: 5.15.3 KDE Frameworks Version: 5.54.0 Qt Version: 5.11.1 Kernel Version: 4.18.0-17-generic OS Type: 64-bit Open up the program and resize the canvas. The main window will become inactive and stay inactive. The only way to re-activate it is to alt-tab twice. i haven't tested this outside a Latte + Global Menu environment. So I can't be certain that you can reproduce this on stock KDE.
Odd, but I see the same without Latte or Global menu.
I can confirm this on KDE Neon User edition/Kolourpaint flatpak. It also prevents refocusing and minimizing the app by clicking it on the KDE task bar, until Alt-Tabbing/bringing some other app to foreground. If the colour selection area is floated/detached when resizing canvas, it disappears.
*** Bug 409377 has been marked as a duplicate of this bug. ***
A possibly relevant merge request was started @ https://invent.kde.org/graphics/kolourpaint/-/merge_requests/4
Git commit 35c55d4a65e3bf680254dcf417b571cd1ec44353 by Martin Koller. Committed on 22/11/2020 at 21:16. Pushed by mkoller into branch 'master'. Don't grab/release keyboard to get key events. Use setFocus() instead FIXED-IN: 20.12 M +1 -4 kpViewScrollableContainer.cpp https://invent.kde.org/graphics/kolourpaint/commit/35c55d4a65e3bf680254dcf417b571cd1ec44353
Git commit 676899ef3b5749b7acb7b8b278059e99eca09c8b by Martin Koller. Committed on 22/11/2020 at 21:22. Pushed by mkoller into branch 'release/20.12'. Don't grab/release keyboard to get key events. Use setFocus() instead FIXED-IN: 20.12 (cherry picked from commit 35c55d4a65e3bf680254dcf417b571cd1ec44353) M +1 -4 kpViewScrollableContainer.cpp https://invent.kde.org/graphics/kolourpaint/commit/676899ef3b5749b7acb7b8b278059e99eca09c8b