What happens if you maximize and then restore a window while in seamless mode ?
Nothing.
Another idea: open Windows in full screen mode, go to ProgramManager->ControlPanel->Desktop and set "Border Width" to say 3. Maybe you need to change back and forth between two values. The default value seems to be 3. Note that this will not be possible if you are in seamless mode !
If that still does not help: there are entries in OS2.INI like "WIN_RES_x". In each of these there are 4 keys that reference what windows display driver is in use for fullscreen and seamless, respectively. Maybe you will have to manually update each of these to match your settings in system.ini.
I already did what you said, but no helps.
Even though I renamed my MDOS dir and copied a MDOS dir from other OS/2 installation and reset to VGA mode, they do not change anything.
I don't understand that the border width of a seamless window comes from where.