SUMMARY
When dragging and dropping from one application to another, the cursor does not correctly indicate if the drag-and-drop target is valid.

Within a single application, (dolphin for example) the cursor displays whether the drag-and-drop is a valid action, and changes between a 'no way' syymbol and an arrow with a + depending on if the target is acceptable. For instance dragging to the window borders is not acceptable and will not work.

When dragging to another window, the cursor necessarily passes through the window border and changes to the 'no way' symbol. After exiting the window, it remains in this state, regardless of where you try to drag and drop, or if the target window will accept the drop.

STEPS TO REPRODUCE
1. select a file in dolphin
2. drag it to the desktop
3. observe the cursor states during the drag
4. drop the file to the desktop
5. observe that a menu pops up, accepting the drop, even though the cursor indicated it was not going to work.

OBSERVED RESULT


When dragging to another window, the cursor necessarily passes through the window border and changes to the 'no way' symbol. After exiting the window, it remains in this state, regardless of where you try to drag and drop, or if the target window will accept the drop.

EXPECTED RESULT

The cursor state should indicate if the drop target is valid, both inside and outside the originating window.


SOFTWARE/OS VERSIONS
Linux/KDE Plasma: Arch
(available in About System)
KDE Plasma Version: 5.15.90
KDE Frameworks Version: 5.58.0
Qt Version: 5.13.0

ADDITIONAL INFORMATION

This behavior differs somewhat when originating from an XWayland window - the cursor appears to change in response to the desktop accepting the drop, but if the cursor is moved over another window and then back to the desktop, it stops updating.