the mouse cursor should not pop up on
its own, as long as ShowMouseCursor is
set to false. it should always respect
that setting.
I agree with that, sure. The current behaviour is counter-intuitive and makes workaround implementation fiddly. Essentially, for as long as the Cursor behaviour tick box is left to its own devices, I’d rather have the controller have full control over the pointer.
Admittedly, I did not test it. Knowing how UMG works, though and how often it takes over the controller (during drag&drop, for example), this is a half-expected, if undesired behaviour.
One of the many quirks of UMG, I guess.