holding Shift or Ctrl always allows multiple instances

[TRAFFICBLOWS]

It's nice to have all opened files to go into the same workspace, but when two separate workspaces are desired, it's a pain in the neck to temporarily enable "Allow multiple instances" in preferences, only to disable it when one more instance is opened up. Actually, then you have two places where you have to disable it.

If you press Shift or Ctrl while clicking on Textpad.exe, a new instance could open whether or not "Allow multiple instances" is enabled. This would kinda work like internet pop-up stoppers, where you allow a pop-up to happen when you hold down Shift or Ctrl.

[Jason Shallcross]

Looks like this has been suggested more than once, but it's very difficult to track down others in the search results because the keywords like "new" are so ambiguous and not everyone would think of "instance".
So I think this suggestion is probably more popular that it seems.