Detect mouse leaving application's window in pure QB64

[James D Jarvis]

Isn't the lack of mouseinput the easiest way to tell the mouse isn't in the window?  In the image linked here there are 3 runs of the same little scribble application overlapping. The pixels only get drawn when the mouse is in the top overlapping window.  I'm just a little confused on the reason to track the lack of mouse  input in the window when ... none gets reported if the mouse isn't in the window. Am I missing something?