G4P can't handle multiple opened sketches on my mac

If I open 2 sketches in Processing on my mac, “G4P GUI builder” gets confused and if I open it while focused on one project, it may bring the “gui” of the other.
This forces me to close all other sketches and try again to get the correct “gui”.
Am I alone on this or did it happened to anyone else?
Is it a Mac-specific issue?

You cannot use GUI Builder to design GUIs for 2 or more sketches at the same time, it is just a limitation of GUI Builder.

Understood !!