Mac OS
Controls like the mind map dropdown that allows you to select child mind maps, and the title bar of the window, are transparent. It’s a pain in the patootey to click on something only to have to scroll that thing to then be able to click on it. It happens more often than I’d like to admit. I now overcompensate so I lose more of the working area that I probably have just to ‘play it safe’.
Edit: Just to be clear: Display the title bar and the dropdown clickable area for the child mind maps, that way it is clear where a user can click for mind map control and where they need to click to move the window or choose a child mind map.