Detecting whether the X server VT is the active one

[Michael Thayer]

On 05/03/14 19:50, Adam Jackson wrote:
> On Thu, 2014-02-27 at 16:01 +0100, Michael Thayer wrote:
>> Another problem that I am running into is that the X11 client part of
>> our Guest Additions needs to know whether or not the X server VT is
>> currently the active one, for example so that it can disable our
>> "seamless windows" functionality if the server is switched out.
>> Currently we do this too with a hack in our DDX.  This only needs to
>> work with a standard X.Org server, so I thought about adding code to the
>> server to add and update a root window property to pass on the
>> information.  Does that sound like an acceptable solution, and if not,
>> does anyone have a better one?
>
> I think that sounds reasonable.  There's already cases of people getting
> confused about things like XGetImage not working when VT switched away.
> If we're going to preserve that behaviour - which I do wish would
> eventually be optional - it's reasonable to give clients a way to know
> that it's happening in-band with the rest of X.  (Consulting systemd or
> consolekit or whatever isn't generally useful, since if the client is on
> another machine there's no way it could talk to the appropriate daemon.)

Sorry, it has taken me a while to get around to this (too many tasks 
competing for my attention!)  A patch to do this is coming up.  In order 
to reduce the area of code touched (and in particular so as not to have 
to register the property at initialisation time as per XFree86_VT) I did 
this as a property which is created when the VT is switched out and 
removed again when it is switched back in.  Please tell me if this is 
acceptable or if it is too hack-ish.

Regards,

Michael
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