While testing my uninstaller patch, I ran into the issue that was a problem in Win95, where the uninstaller did not handle deletion of it's uninstall registry key. What I did was install a program that I new put it's registry key under HKLM. Then I copied that key to HKCU. Then I installed a program that I knew put its key under HKCU and copied that key to HKLM. Then I uninstalled each one with the copied key.
The program's uninstaller removed the key that it was instructed to take out, but left the other one behind.
My question is this. If an uninstaller (outside of my test environment) does not remove it's registry key before the process exits, should our uninstaller check for that after the process exits, and go ahead and remove the key, or should we make the user press the uninstall button again and ask them if they want to remove the key (like we already do, in the event they manually removed the program, by deleting the folder)?