Hi, Gang,
What follows is from my system notes. I am using a somewhat more rigorous style to keep notes on things I do to systems under my control now so that I can go back in my notes and expect them to have some consistency and usefulness to me. This details a work-around I have applied to "fix" the problem until I know whether or not it can be actually solved.
UPDATE - 10 Jan 2011: Discovered that extended or cloned desktop operation has adverse effects on Xine and other video player playback. MPlayer still works, but given the sheer number of other things that depend on Xine in a PCLOS install of KDE-4, I'm playing it safe for now until I know more about what's going on with this. I've had to comment out my added lines in .bash_profile and suspend use of my second monitor to restore Xine playback.
Later On,
D
Tagging for Search: {PCLOS KDE-4 2010 Dell Latitude D620}
Swapping VGA1 to Secondary Display in Extended Desktop Configuration
2011.Jan.09
Rev. 1.00
1.0) BACKGROUND:
The system under consideration is my Dell Latitude D620 notebook computer, hostname: falcon. Attached to its external VGA port (VGA1) is an Acer 15.4 inch flat panel which I want to use as the secondary display of an extended desktop configuration. Thus far, I have not uncovered any combination of switch settings in KDE's Control Panel (started from the “Configure Your Desktop” widget in the panel) which will make this possible. No matter what I try there, the system insists on making the external flat panel the Primary monitor and extending the desktop onto the laptop's screen (LVDS1).
The operating system for falcon is PCLinuxOS 2010.07, KDE-4 “Regular Edition” with all installed packages updated this morning. The video card in this consideration is an Intel 955GM, using the default (i810 or later) driver set.
2.0) CAUTIONS & WARNINGS:
After some preliminary research, I made certain changes to the startup script /home/horus/.bash_profile to accomplish the swap. I can't help but wonder if there are better ways of doing this (perhaps in xorg.conf?). This edit would need to be made for every user of the system (or placed in a more global script) to affect other users.
As with all work-arounds of this type, this one is specific to the hardware platform outlined in the previous section. Different hardware may yield different results, and script modifications given here for this hardware should be carefully reviewed and considered as to applicability before use elsewhere.
{EDIT} See the above note for UPDATE - 10 Jan 2011 if you have not already done so! Bad things can happen here. At this point, I have to say that, honestly, more research is needed before I will be comfortable using a dual-monitor setup on this hardware again. Kinda makes me wish I had opted for the D620 with the NVidia video card (but those were supposed to have big problems with overheating... (grumble, grumble))
3.0) INITIAL CONDITIONS:
Initially, the system was operating with both displays enabled, and the primary display “cloning” the secondary.
4.0) TROUBLESHOOTING:
I first considered the possibility that the CMOS settings for primary and secondary display might be influencing things, so I set the system CMOS to make the computer's internal display the primary, but this still had no effect on which options KDE made available through its Control Center.
Searches I conducted at pclinuxos.com's fora initially proved less than illuminating, but when I tried Google, I came up with a link to a discussion on another forum which mentioned using xrandr to set the parameters needed to configure the system as desired.
The only drawback I could see to this approach was that it was necessary to include the xrandr commands into a startup script that would run when users logged in. The script .bash_profile is such a script, and well suited to this purpose. I used joe to do the edit, but any plain-text editor (e.g., vi, emacs, Kate, leafpad) should make it possible to edit the file.
5.0) CORRECTIVE ACTIONS:
The following lines were added to the end of the /home/horus/.bash_profile script and saved:
# Extended Desktop Setup Commands
xrandr --output VGA1 --off
xrandr --output LVDS1 --auto --primary
xrandr --output VGA1 --mode 1366x768 --right-of LVDS1
The net effect of these is to first turn off VGA1 (the external flat-panel) temporarily, then assign LVDS1 (the laptop's display) as the primary display and set it's mode to its automatically sensed settings, then re-activate VGA1 in 1366x768 mode (its native resolution) and place it virtually to the right of the LVDS1 as an extended desktop.
6.0) AFTERWORD:
As was mentioned previously, this is a work-around. I'm sure a better solution exists and I just haven't had the time to find it yet. Those unfamiliar with xrandr and its parameters and switches would benefit by reviewing its manual pages (by typing man xrandr at a bash prompt).
