The Delphi IDE (version 5) disappears from the taskbar (button) when switching virtual desktops. Even worse, when it's minimized while switching I cant get the window(s) back (not in alt-tab list) and have to go and get the window back from the default desktop. I added delphi32.exe to the registry keys _NeverSubClassPrograms and _NoCloseWhenHidden and indeed it doesnt get the pin to make it sticky, but this doesnt solve the problem.
Did you enable the taskbar sort option in "Settings", then "Virtual Desktop Toolbox"? Is there a way to get a trial version of Delphi 5? What is the name of the Dephi 5 executable?
If this name is Delphi.exe, you can try this:
Run the registry editor, go to the HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\R2d2KernelAuthori ty\Parameters key, edit the _MultiWindowsPrograms value (create it with a REG-MULTI-SZ type if it doesn't exist; look at MultiWindowsPrograms for a template) and add a new line *\Delphi.exe (if Delphi.exe is the name of your executable). Restart your computer.
Let me know if it works so I can add it to the setup program.