TestField update while mouse drag

Win10; Xojo 2024 1.1

When I drag the mouse in a canvas on a DesktopContainer, I want to change the UI.
It seems that while the drag event is firing (continuously) timers are stopped.
Even a thread and UnserInterfaceUpdate is blocked.
Any idea or any hint where to search for a solution?

The problem is when using mousemove event, I can not get mouseup event triggered.

Thanks a lot!

WinMouseFilterMBS is a clean and simple solution.
I can check the button state app wide.