I can reproduce it with b4a or b4j on my windows 10 64 bit machine reliably. When I hover over a keyword and the window is active the hint message comes up as expected. Moving the mouse to the left or up the hint disappears almost immediately. Moving the mouse to the right or down requires about 2 inches of mouse travel (on my screen) before the hint disappears. Now, if you have another window open and active that covers this two inch travel distance then the hint stays on the screen when you move the mouse over to the new window. It's 100% repeatable. The mouse position is no longer being reported to the b4a or b4j program, instead the mouse position is being reported to the active overlapping window. The hint stays on the screen because b4a thinks the mouse is still within the distance that keeps the hint on the screen. If the measuring distance can be reduced it will minimize the problem. Hope this helps!!