I made a few changes to my setup tonight which have made me very happy.
Installed Picasso96_21b:
This upgraded my rtg.library and Picasso96Mode. Not sure about the variable setting program. I thought I had the latest installed already, but I was obviously mistaken.
Played with PicassoModeTNG:
Still working on understanding this one... doesn't seem to do things the way I think it should.
Increased the pixel clock of my 1280x1024x24 mode to the maximum (85.03MHz IIRC.) This increased my refresh to 48Hz.
I was surprised that the Picasso96 upgrade only changed the rtg.library and P96Mode by a minor version bump, but I believe that this alone is what eliminated the random graphic corruption when clicking icons. My Workbench now works 100%!
Before this corrected my display corruption, I played with bumping down to HiColor mode, but for the life of me I could not get the screen to fill the monitor vertically.
Also, I lied about being a week to test the 15KHz input on SVGA on the Dell 2001FP. I had good intentions, but some systems haven't seen the light of day since my move in October 2006 due to various happenings, and now it seems they won't make it out due to the possibility of another move. ::sigh:: Of course, at this point it's probably moot, anyway, since wide-screens are the norm anymore.