glist_doreload shouldn't trigger GUI window creation
When the user makes changes to an abstraction, Pd goes through the list of toplevel patches and reloads all instances of that abstraction. But it does this by opening the window for each abstraction, selecting the relevant abstraction, cutting it, and the undoing the cut. To achieve this, Pd has to make the subpatch visible, then make it invisible when it's finished.
This causes unnecessary messages to get sent to the GUI which temporarily flash new windows on the screen. Luckily the subcanvases themselves aren't mapped, so its just empty windows that show up. Still, these GUI messages should be suppressed.