[X2Go-User] Windows x2go client displays at incorrect resolution

[Davis, Jean-Paul]

I _finally_ found the solution to this problem, simply by searching online for VcXsrv and hi-dpi.  It turns out to be a Windows 10 compatibility issue.  All I had to do was edit the properties of the VcXsrv.exe executable file, by checking the box for "Override high DPI scaling behavior" on the Compatibility tab.  Then x2go produced a display at full resolution of the client's physical display (2560x1440).  Setting the DPI to 192 in my x2go session preferences causes scaling of 2 for the UI.  Now if I could only specify a fractional scaling between 1 and 2... (it looks like this will be possible in just-released MATE 1.20, but who knows when that will be available in RHEL 7).

> 
> I have not followed up in the past nine months because my remote sessions
> are somewhat useable in the current state, but it still annoys me to no end, so
> I just tried looking at it some more.  I do not have a solution.  Here is a recap of
> what I have and have not figured out.
> 
> When the Windows client display preferences are set to full screen (everything
> else default), the remote desktop session that appears on the client's physical
> display thinks it is connected to the "default" video output, for which xrandr
> (run in a terminal window, inside the remote desktop session) shows a
> maximum resolution of 1920x1200, with a resolution of 1280x720 selected,
> which is exactly half the width and half the height of the physical display on the
> client (2560x1440). The xdpyinfo command reports a dpi of 75.  If I set the
> client preferences to 192 dpi (corresponding to physical display on client), the
> resulting remote desktop session is still 1280x720, but all elements are scaled
> up by a factor of 2.  It is my understanding that this is the default scaling
> generated by X when it detects (or is given) a dpi larger than some value that it
> considers to be hi-dpi.
> 
> I have seen suggestions about creating a new display section in xorg.conf on
> the server for a virtual monitor, but most people report that does not work.  I
> am not knowledgeable enough to understand exactly how x2go interacts both
> with the X-server on the x2go server (RHEL 7.4) and with the X-server (VcXsrv)
> on the x2go client (Windows 10).  I'm thinking that somehow, if possible, I
> need to change the "default" video output used by one or the other of those
> X-servers to allow 2560x1440 resolution.  Does anyone know how to do this?
> 
> Even if I get that to work, I may still have an issue getting the MATE desktop to
> use my desired hi-dpi scaling (instead of just forcing everything to double).
> Inside the remote MATE desktop, I am not able to change any display
> preferences; it always produces an error related to the versions of xrandr
> (display preferences requires at least 1.3, server version is 1.2, though program
> I'm actually running is 1.5).
> 
> And would it be worth my time to try again building x2go from the Arctica
> project?
> 
> Jean-Paul