Multiple displays with VNC for Windows
Tue Jun 10 09:08:00 2003
> -----Original Message-----
> From: Ross Presser [mailto:email@example.com]
> "Scott Huber" <firstname.lastname@example.org> wrote in
> > First off, let me say that I am a complete VNC newbie. We use it in a
> > Windows-only environment to remotely administer pc's at our various
> > sites around town. And even at that, we only use the default
> > VNCViewer settings. Just the other day I realized there is a
> > web-interface to VNC.
> > On to my question... Upon perusing the main VNC website and finding
> > this list, I've seen information regarding the ability to access
> > multiple displays, but it all seems to be related to xNIX boxes. I
> > have several pc's that have two and even three displays with certain
> > applications set to open on respective displays (i.e. Internet
> > Explorer opens on the third display). But with the standard VNC
> > settings, I can only access the primary display. How can I access the
> > other displays?
> When you refer to "pc's with two and even three displays" I'm guessing
> you mean multiple monitors. These are not the same as multiple displays
> the unix sense. A display in the unix sense refers to the desktop canvas
> that windows are drawn on, and to the keyboard and mouse inputs that the
> display accepts. Usually there is a separate display for each user
> concurrently on a multiuser unix machine.
Well, actually there is something like multiple display and multiple monitor
on unix. If you carefully look to the $DISPLAY setting in X11, you see
something like "localhost:0.0" or "vncserver:1.0". If you translate this to
(pc-style) hardware, then it is somethign like this: The first number is for
the X11-server, a combination of 1 keyboard, 1 mouse and 1 or more
display-adapters. The second number is to address the "1 or more"
display-adapters. If you have a display-adapter with multiple monitors, it
is either configured as 2 (virtual) display-adapters, or configured as a
single large screen spread over the monitors.
In the above, I use the next terms:
$DISPLAY the address for the windows.
display-adapter the hardware in the (isa/pci/...) slot.
monitor the screen you look at.
> In this sense, WinVNC does not support more than one display per host.
WinVNC does not support more than one $DISPLAY setting per host since there
can run only one WinVNC server per host.
If you have multiple monitors connected to one display-adapter resulting in
a system where you can have a single window spread over both (all?)
monitors, I think vnc only sees a single-large display and forwards that,
since it just sees the entire screen.
This is kind of like a laptop/lcd-monitor with a panning display (large
screen with smaller viewport or such) where you cannot see the entire
display at the monitor. VNC just forwards the entire display, not what just
happens to be viewable in the monitor.
If you have multiple monitors connnected to multiple (virtual)
display-adapters resulting in a system whre you can move the mouse and
windows from one monitor to an other but not have a single window spread
over multiple monitors, I'm about sure vnc only forwards the first part
(primary monitor) since it does not see the other ones (as it does not look
> Perhaps your next question, then, will be "How can I get VNC
> to display
> windows on other than the primary monitor"? I do think that it is
> possible, though it is frequently asked.