The way I finally tested this was to write a little routine. I added a Popupmenu control to the main window of his project. Since I placed this code within the MouseEnter handler, every time I moved the pointer into the Popupmenu's area the window list was refreshed. As I played with his program I periodically went and checked the current window listing. That made me realize the other hidden windows were interfering with REALbasic's understanding of which was the frontmost window and causing it to draw incorrectly.
Closing gets rid of the window while hiding it just makes it invisible.
Closing an unused window also saves memory, because an active window is still using memory. The window may or may not be visible, but just referring to it makes it active. In John's case when his program was launched he would read in items from a preference file and set variables in a hidden window with those settings, effectively activating the window though it was invisible. A cleaner approach is to store the setting in a global variable which your window can read when it is opened. That's all for this week.