Ok, so this might be intentional, and not a bug, but I think it is very annoying. If you have an instrument plugin loaded and click on the Plugin tab, the external editor window will always open immediately. This is ok the first time you load the instrument, but even if you close it, it keeps reopening every time you visit the tab.
What makes it extra annoying is that it happens even if you just switch to another window and then switch back. I personally think that the external editor should remain closed until you open it manually instead of popping up on its own all the time.
