Left and right mouse button lag

In my previous post I told that I was experiencing about 50ms latency for left and right mouse clics. After some investigations I discovered that the problem was located in xorg.

It appears it’s not a bug, it’s a functionality called “3rd button emulation” that is useful with a 2 button mouse. Xorg waits up to 50ms to see if both left and right buttons are pressed, and in case it is, it generates a middle button press.

It’s nothing to say that this implementation is lame and should be disabled by default.

Following bug reports were filled by people complaining about that behavior:

Although a real middle button press is enough to disable the functionality (not persistent), it’s possible to disable it by default (works for Ubuntu 10.10):

sudo gedit /usr/share/X11/xorg.conf.d/20-mouse.conf

Copy-paste to following lines:

Section “InputClass”
Identifier “Mouse0”
MatchIsPointer “true”
Option “Emulate3Buttons” “false”

Save, and Restart!

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