Hi there,
I think I found a bug in PCEm, running Windows 3.1x on PCEm V8.1.
When I run a DOS application within Windows 3.1x and change it from full-screen to windowed mode (CTRL+Enter), I get video corruption in the DOS application's window.
If I edit the PIF file for the DOS application so that it launches in windowed mode immediately, I get a random result ranging from occasional success through to GP faults/integrity violations or complete lock up (of the emulated system that is).
I have tested this on Generic AMI 386/486/WinBIOS configurations, with both Trident 8900D and Tseng ET4000 roms (so basically the core configurations available if you just stick with what's downloadable from Sarah's website). For each configuration I also played around with all sorts of BIOS settings, plus tested DOS versions 5.0a and 6.22 + Windows versions 3.1 and 3.11 with a variety of video drivers/resolutions/color depths. Even with a bare-bones boot (himem.sys only, no emm386/mouse/smartdrv/etc.) the bug still persists. Screenshots are attached so you can see what I'm getting.
I'm not looking for a fix, just thought I'd let Sarah and contributors know seeing as nobody has mentioned this bug (so far a I can see that is).
But while I'm here may I say how awesome this little emulator is. Sarah and contributors: you have a real talent, thanks for sharing this with folks like me who wouldn't even know where to start. I do code a bit myself, but it's all so high-level compared to this!
M