Fullscreen spanning a program across 2+ monitors?

thinkpadboi · 03-20-2020, 01:41 PM

I'm now working from home indefinitely, and that means having to remote into work, which means having to deal with Citrix. I currently have Citrix installed in a podman container that I can ssh -X into and run remote desktop. The only problem is, I can't find a way to get the window to fullscreen across both of my monitors. I can drag / resize the window very close, but if it snaps or I try maximizing it, it will jump to fullscreen on one screen only. I am using Fedora 31 with Xfce and/or i3.

Ideally, what I think would be the best solution at this point would be lightdm / xfce running on vt1 and having Citrix run without a window manager and forced to span monitors on a separate vt. However, I don't have a good enough understanding of how X works to achieve this. It seems to also interfere with my X session on vt1 when I experiment with running X on other vt's at the same time.

How can I do this?

business_kid · 03-21-2020, 06:28 AM

The short answer is that I don't know if you can. The way you set stuff like that up is in /etc/X11/xorg.conf.d/, which supersedes the default stuff in /usr/share or wherever that is hidden.

So open 'man xorg.conf' on one terminal, and 'sudo <editor> /etc/X11/xorg.conf.d/20-video.conf' in another terminal, and draft the video section. Have one ServerLayout, and a Monitor, Device, & Screen section for each Monitor, card o/p & configuration you might use. When X boots, it feels around and configures whatever it finds. I think the sticking point may well be having one window spread across 2 screens. You may be able to do that this way: xterm (and I presume other programs) accept X & Y dimensions as options. So if you ran 'xterm -geometry 3840 1080' you might get it spread across 2 hdmni screens. Those xterm options are guesses, btw - check the man page. Then anything started in the xterm has it's size set.

thinkpadboi · 03-23-2020, 08:04 AM

Interesting update... I found this reddit post where someone mentioned adding 'force-xinerama yes' and assigning a keyboard shortcut for 'fullscreen toggle global' to their i3 config. Without messing with Xorg conf files or force-xinerama, and just using a shortcut for 'fullscreen toggle global', I can get a terminal, Firefox, etc. to span both monitors. In that case, it has to be something about this particular window that is causing issues. Here's the xprop information from it. I wonder if it could be related to WM_SIZE_HINTS? Can I somehow force it to ignore those?

Can you explain what explicitly defining monitors in the Xorg conf files does, as opposed to letting them be set up dynamically?

Code:

_NET_WM_DESKTOP(CARDINAL) = 3
_NET_WM_STATE(ATOM) = 
WM_STATE(WM_STATE):
		window state: Normal
		icon window: 0x0
WM_PROTOCOLS(ATOM): protocols  WM_DELETE_WINDOW
_MOTIF_WM_HINTS(_MOTIF_WM_HINTS) = 0x2, 0x0, 0x0, 0x0, 0x0
WM_CLASS(STRING) = "Remote Desktop Connection", "Wfica_Seamless"
WM_LOCALE_NAME(STRING) = "C"
WM_NORMAL_HINTS(WM_SIZE_HINTS):
		program specified location: 0, 0
		program specified size: 1920 by 1080
WM_CLIENT_MACHINE(STRING) = "0f362e601c33"
WM_ICON_NAME(UTF8_STRING) = "[redacted] - Remote Desktop Connection"
WM_NAME(UTF8_STRING) = "[redacted] - Remote Desktop Connection"
_NET_WM_NAME(UTF8_STRING) = "[redacted] - Remote Desktop Connection"
WM_HINTS(WM_HINTS):
		Client accepts input or input focus: True
		Initial state is Normal State.
		bitmap id # to use for icon: 0x2a003a0
		bitmap id # of mask for icon: 0x2a0039e

business_kid · 03-24-2020, 05:22 AM

X is good at interrogating the monitors and setting up a good safe mode.
When you have two or more monitors, defining them allows you to set things like:

A Virtual screen and which part of it they are.
Which is the Primary monitor
Options like rightOfScreen1
These can be different for different mo9nitors

At one stage I was plugging in a 1280x720 projector or 1920x1080 hdmi screen or nothing into my hdmi port. It was possible to overscan on the projector, but I didn't want that. There may have been a difference in refresh rates, but you can set that up. As it happened, I had them both on the right, but I could have had one of them them overlapping. Read the video section on 'man xorg.conf' (if they haven't renamed it) and look at the options.