I am running GNOME 3.26 with GDM on X.org. I have an external monitor at work and I am running my Laptop (Dell XPS 9550) and the monitor in about the same resolution (regarding dpi; both around ~1900x1200 px).
When I unplug the monitor my laptop switches to a much higher resolution: 3200x1800 px. Most apps are working fine (Nautilus, Firefox, Chrome, GNOME apps, ...), but some especially HiDPI aware apps like PHPStorm, Rambox, Typora (Java and Electron apps) show a much too small font and icon size.
The annoying thing is, I have to restart these applications to make them aware of the new resolution. Is there a way to trigger this behavior without restarting the applications?
I know that I could run the laptop in standalone mode in the same resolution as when I have the external monitor plugged in, but I'd like to use the higher resolution, the above setup is actually already a workaround for the same problem, when running two displays with highly different dpi.