Dual Monitor on Ubuntu

The dual-monitor problem bothered me from time to time on my office desktop. The maximum screen resolutions are different: one is 1280x1024, and the other is 1600x1200. There is only one dual-monitor option in screen resolution setting, which is 3200x1200, however the monitor with the resolution of 1280x1024 does not support that.

Later, I figured out the reason might be that I selected the one of 1600x1200 as the primary monitor, so that the dual-monitor resolution was based on that. Finally, it worked again after I changed the primary monitor by switching the two cables.

Hacking xorg.conf also helps. I need to add a line in Section "Device" saying:
Option "ParisModes" "1280x1024+1280x1024"

Disable IPv6 for Firefox

I find it pretty slow connecting to python.org. Actually this is why I asked my advisor for a Programming Python book. However, this problem does not show up on my laptop at home, so I guess it is a network configuration problem.

When doing a `telnet www.python.org 80', i saw telnet trying connecting to the IPv6 address of that website, and eventually timed out. Then, it tried the IPv4 address and got succeed immediately.

I disabled IPv6 for Firefox by changing the preference named `network.dns.disableIPv6', and everything went well. The problem may be caused by the router does not support IPv6. I'll shoot Daisy an email asking about this.