Try changing your cursor to a different one using systemsettings. It works mostly everywhere in KDE. However, this cursor update is not reflected on window borders. For example, try dragging the window using the top bar. You'll notice the cursor changes immediately from the one you wanted to the default one.
Ordinarily, this would just be a silly cosmetic bug of little consequence. However, in the case of HiDPI, this bug means that the cursor goes from being a normal size to being extra small (and thus unusable) when you mouse over a window border.
This causes significant usability impairments.
Interestingly, the issue with *which cursor* was fixed by running `ln -s /usr/share/cursors/xorg-x11 ~/.icons`. This seems most likely an unrelated bug, and I'll file another patch for it elsewhere.
HOWEVER, the main issue with this bug here still remains: the size of the cursor remains very very small. Kwin window decoration borders do not respect HiDPI settings for cursor size.
Created attachment 101063 [details]
Animated gif showing the issue
A workaround for this is changing it from "Resolution Independent" to an explicit size 48 in the Cursor Themes systemsettings module.
This isn't a super pretty solution, however.
The general problem with cursors is the fallback strategy: if a cursor is missing it is looked up in the (system) fallback theme. This means if the cursor is missing in the theme you get the fallback. This can be fixed in two ways: fix the theme by providing all required symlinks or have the same theme set as the fallback theme. In that case our software selection works.
Actually I fixed this initial problem of finding it in the theme (see comment #1). The issue, now, is that when "resolution dependent" is selected, the cursor's correct size is not selected on HiDPI displays.
*** Bug 390626 has been marked as a duplicate of this bug. ***
*** Bug 376245 has been marked as a duplicate of this bug. ***
Still present on Plasma 5.12.2.
It happend to me too. but in my case happend in a HiDPI reescaled interface, pointer doesn't stay at same size on window decoration.
Interface reescaled: 1.5
Distro: Manjaro KDE (but I faced same issue in Kubuntu an OpenSUSE)
Plasma version: KDE 5.45.0 / Plasma 5.12.4 (also i faced same issue in older versions too)
This issue report is quite old. Can you please confirm, that it still persists with KDE 5.23? Is there something that can be done about it?
(In reply to kde.org from comment #10)
> This issue report is quite old. Can you please confirm, that it still
> persists with KDE 5.23? Is there something that can be done about it?
I just tried this in Plasma Wayland 5.24:
1. Open System Settings / Appearance / Cursors
2. Change the cursor size (I changed it from 36 to 24)
3. Click apply
4. The cursor size does not change while the cursor is within the System Settings window
5. The cursor changes to the expected size when hovering over the window borders
6. Closing and re-opening System Settings does NOT change the cursor size in the window
7. XWayland clients behave exactly the same (the cursor size inside the window doesn't change, but gets smaller/larger in the borders)
As far I can remember, I think that this is because the system needs to reboot or restart the entire session but the problem is there is not a message or sticky message to inform the user that needs to reboot.
What's described in comment 12 sounds like a duplicate of 420859.
*** This bug has been marked as a duplicate of bug 420859 ***