Re: [PATCH v2] ui/gtk: Allow user to select monitor number to display qemu in full screen through new gtk display option

[Gerd Hoffmann]

  Hi,

> " Your new option argument seems to count monitors from 1, while GTK counts 
> them from zero.  Why the difference?"
> sweeaun: It is due to gtk_window_fullscreen_on_monitor monitor index is 
> started from zero. I am not using zero as starting index of new option 
> argument to make easier for user. Example, if there is 2 monitors, then 
> argument option can be monitor 1 or 2. Last number will matched with total 
> monitors which can avoid confusion for user. That is my thought.   

Start counting from zero makes sense too.  Matter of tasts.  We have
examples for both in the qemu source tree.  So, whatever you pick, this
clearly needs documentation (in ui.json option description).

> "Your documentation states that @monitor applies only "in full screen", but 
> this code is not guarded by if (opts->full_screen).  Why is that okay?"
> sweeaun: It doesn’t need to be guarded by if (opts->full_screen), as 
> gtk_window_fullscreen_on_monitor will enable the full screen by itself.  

Well, wouldn't it make sense to have monitor=<nr> work for both
full-screen=on and full-screen=off cases?

> sweeaun: Based on my observation, when specific monitor device disconnected 
> after QEMU launched on it, QEMU application will not be visible but QEMU 
> application still running and screen framebuffer size is not being changed at 
> all. QEMU application will be visible once you connect back the monitor. 

Well, that probably depends on the display server and might even be
configurable.  I've seen different ways to handle that, most common ones
being (a) do nothing or (b) trying move all windows to the monitor which
is still connected.

I don't think qemu has to worry much here, and trying to automatically
adapt to hot-plugged monitors might even have bad interactions with
whatever the display server is going to do.

take care,
  Gerd