I'm doing a lot of switching between the two these days. Maybe this is intentional, but when I have one open already and I attempt to activate "stir" or "experiment" from the opposite, I don't get any sort of error message and the current window (experiment or stir) just stays open and the one that I want to open does not open.
There's definitely certain times where this would be the right thing to do - like when I'm in the middle of another experiment - but mostly I just want to switch between the two to see how much more of x I need to make.