Why calculations stop when the plot window is minimized

Hello, everyone!
I have been using FreeFem for many years (on Windows) and I am very grateful to the developers for this package! But after all these years, I finally decided to ask about one very annoying feature of FreeFem.
Why do the calculations stop if you minimize the graphical window, in which the plot is displayed? Is it a bug, a feature, or some option that I cannot find in the documentation (the wait option of the plot function is set to false, by the way)?
If I expand the plot window, the calculations resume. It seems that if ffglut doesn’t find the plot window to send data to, it stops the whole process.