view: reuse current instance option
I frequently open a book in the viewer (V) while updating metadata manually to find something on a inner page, then move to the next book. Note: the viewer opens on the second screen so I can view both the Main GUI and the current book page.
The issue is a new instance of the viewer is launched (from the GUI), which uses resources and adds clutter
Having a tweak to reuse (or close previous if open) the viewer would be handy. Open-With might be used to force a second instance if the tweak was set