Okay, try out the attached Debug3 on your system. In this version, I'm not trying to position the preview window until the first time you try to show it. The position code is in its form_load routine instead of the main window's form_load routine.

Try it out and make sure you can show/hide/re-show the preview window.

If this works, I'll refine it for the next version (and probably add saving/restoring window positions while I'm at it). And I'll curse Microsoft a bit, too, because there's no reason it should've worked on everyone else's system but not on yours. I hate all this FM you have to deal with when you code for Windows.

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Tony Fabris