[ltp] RE: 2nd independent *not mirror Monitor with ati mob radeon 7500 T41

David Winick linux-thinkpad@linux-thinkpad.org
Sun, 04 Dec 2005 12:15:34 -0500


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Alejo,

The following bit of text is something I have been preparing to post
elsewhere (for OpenOffice users, FedoraForum.org or ThinkWiki.org,=20
since no one else has seemed to figure this stuff out well enough to
explain it), but hopefully  you can extract what you need from it.=20
Note the difference in video cards, however.
...

I recently defended my dissertation on a T41 (w/ FireGL 9000), using
OpenOffice.org2 on a dual-head setup.  Impress doesn't really support
dual-display, but I tricked it into showing the slideshow on an external
projector [the device at (x,y)=3D(0,0)], while keeping the main window
visible on the LCD screen (to view notes, and for navigation / jumping
among slides to answer questions).  Your screens may differ in
dimensions, but not in bitdepth, because Xinerama is used (rather than
defining separate 'screen's).

Here is my recipe, from Fedora Core 4:

# yum --enablerepo=3Drpmforge --enablerepo=3Dextras vnc x11vnc
# vim /etc/X11/xorg.conf, to modify ServerLayout:

	Section "ServerLayout"
	        Identifier     "Multihead layout"
	        Screen      0  "Screen0" RightOf "Screen1"
	        Screen      1  "Screen1" 0 0
	        InputDevice    "Mouse0" "CorePointer"
	        InputDevice    "Keyboard0" "CoreKeyboard"
	        Option      "Xinerama" "on"
	        Option      "Clone" "on"
	EndSection

And create an appropriate Screen1 section to describe the external
device which is connected.  X11vnc was used to show me, on my LCD, what
is being shown behind me on the big projector screen.

issue#1:
icons & desktop background spread across both screens, plus invisible
area if screens differ in size (not really a problem, just make sure
nothing is on desktop that anyone shouldn't see)

issue#2:
current page on main window does not keep up with or control that of
slideshow screen (use your mouse to move between screens and thus to
define the active window)

When an Xorg starts, it checks the port for an external device.  If it
cannot detect one, it disables the Xinerama extension, and your desktop
should just look unchanged.  This is why you see the 'mirror of monitor'
affect that you mentioned.  If Xorg does detect an external device, then
you should be able to move your mouse off the left side of your LCD, and
see it show up on the external device!

On a ThinkPad, or any machine with BIOS that will recognize and use an
external device as an alternate display, do not boot w/ external screen
plugged in; instead, plug in prior to starting X in order for Xinerama
to work (otherwise defaults as mirroring the LCD).  What I usually do,
just after plugging in to the projector, is logout, hit
Alt-Ctrl-Backspace, and log back in; this restarts the Xserver.

Here's the command I'm using to start the 'rear-view mirror':
$ x11vnc -localhost -xinerama -xwarppointer -clip 1400x1050+0+0 -scale
1/3 -bg -q -display :0 && \
vncviewer -ViewOnly -UseLocalCursor=3D0 -name=3DOVERHEAD -geometry 1400x105=
0
+1401-0 :0 &

If your OVERHEAD window opens on the external display, like mine did,
you'll notice it'll show a recursive image of itself!  Then drag it back
over to the LCD screen, onto its lefthand side, conveniently near the
Navigator window.=20

Setup of Impress:
	- move window to right side of LCD, extend height, change to Notes tab,
zoom to fit, select first slide
	- F5 to start slide show, enable/move Navigator to left of main window,
on LCD, hit ESC to exit slide show
	- Slide show settings:  Type=3DDefault, Options as desired
	- Then re-save settings with your presentation=20

Footnotes:

I didn't expect to need Xinerama for this project.  I would've expected
Vino to be able to support what I'm trying to do, but unfortunately, it
always ignores the external screen -- only showing a slideshow on the
LCD screen (slowly too).=20

It is still a little hairy to control Impress under this setup.  During
slideshow mode, not all functions respond to your input, and changing
pages on the slideshow does not automatically change pages on the main
(in my case, notes view) window.  Furthermore, as you move the mouse
around, you must always be aware of which window has focus; Impress is
quite slow at responding sometimes, and can lead to confusion.


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