Hi, why can't I move the Indesign mask with the mouse? if the mouse pointer is not in a precise position on the header bar it is not moved! this is very difficult to use ... in the area indicated in red in the screenshot the mouse does not work and I cannot move the mask .... thanks for any solution to the problem!
As a more general observation, most major apps (Adobe, MS, etc.) have cluttered up the top edge of the app frame so much it's a chore to find a clear spot to grab. It's a minor point that manages to irritate me several times a day, and each time I wish for just one clear strip we can grab easily. (The current versions of Office apps are much, much worse at this.)
Not sure if that addresses the OP''s issue — that there is an actual problem getting a grip even on a clear spot, or that the upper frame is so crowded it's hard to find one.