3 button mouse emulation unreliable in Lenny
I have been using KDE in Debian 5 Lenny since its release around Easter this year. Mostly it is brilliant, my thanks to all the developers. But there has been a persistent problem of unreliability of the 3 button mouse emulation, that was not present in my old Woody system. This shows up worst in KEdit and Konsole, when trying to paste in by simultaneously clicking both mouse buttons. Often, and unpredictably, an unwanted right-click menu appears, instead of the wanted paste. And even worse, one of the menu items is often unintentionally activated, with nuisance effects.
To try to work around this problem, I decided to increase the time threshold for the simultaneous 2 button click. Looking on x.org for guidance on how to do this, I found that it can be done by adding a single line to /etc/X11/xorg.conf. Specifically, as set up automatically, there is a section in this file that reads:
Identifier "Configured Mouse"
I have now altered this section by adding an extra line, so that it now reads:
Identifier "Configured Mouse"
Option "Emulate3Timeout" "10000"
The 10000 is the threshold for the simultaneous 2 button click, in milliseconds, so that the threshold is now 10 seconds. The default was 50 milliseconds. I experimented with various increased thresholds, and found that it is least stressful with this large threshold. What happens now is that if I click the right mouse button and release it, the right-click menu instantly appears. But if I press the right mouse button and hold it, the right-click menu does not appear until a ten second delay has passed. However, perhaps due to a slight electrical glitch or failure of de-bouncing, the right-click menu _sometimes_ still appears unwanted immediately, when I press and hold the right mouse button, just as if I had released it. But because I am no longer under any pressure to press the left mouse button immediately, I can now wait to see that this does not happen, before clicking the left mouse button. Then the wanted paste appears when I release the right mouse button. So the whole process is more relaxed and calm, and less stressful.
It seems that the right-click menu now activates an item if you accidentally release the right mouse button while the pointer is over that menu item, even if you never touch the left mouse button, and this can still lead to nuisance unwanted activation of menu items, if one is not careful. There is also a tendency to release the right mouse button accidentally while clicking the left mouse button, if one is not careful. But at least one can be more relaxed and calm about it, now that one is not trying to click both mouse buttons exactly simultaneously.
You have to reboot the computer for the new option to take effect.
Incidentally, the /etc/X11/xorg.conf set up by Debian does not show the available options. However I found a listing of a similar file that did show the available options, commented out, by searching for change Emulate3Timeout on http://lists.freedesktop.org/archives/xorg/. I learned that Emulate3Timeout was the relevant option, by looking at the log file at /var/log/Xorg.0.log.