it seems that something scales the touchpad x/y speeds to the virtual screen size, without respecting aspect ratio. as this does not happen with other mice, the synaptics driver probably is to be blamed.
there's a crude hack for this bug: mimick the aspect ratio via setting the virtual screen size with xrandr 1) figure out the virtual screen size (the screen size is automatically shrink-wrapped to the smallest possible size to contain all monitors) e.g. on my laptop, with an external monitor connected: ~$ xrandr Screen 0: minimum 320 x 200, current 3360 x 1080, maximum 8192 x 8192 LVDS1 connected 1440x900+0+180 (normal left inverted right x axis y axis) 261mm x 163mm 1440x900 50.0*+ 1360x768 59.8 60.0 1152x864 60.0 1024x768 60.0 800x600 60.3 56.2 640x480 59.9 VGA1 connected 1920x1080+1440+0 (normal left inverted right x axis y axis) 509mm x 286mm 1920x1080 60.0*+ 1280x1024 75.0 60.0 1152x864 75.0 1024x768 75.1 60.0 800x600 75.0 60.3 640x480 75.0 60.0 720x400 70.1 HDMI1 disconnected (normal left inverted right x axis y axis) DP1 disconnected (normal left inverted right x axis y axis) 2) increase the screen size to have the same aspect ratio as your synaptics touchpad (here, it's ~3360/1.938): ~$ xrandr --fb 3660x1734 -- You received this bug notification because you are a member of Ubuntu-X, which is subscribed to xserver-xorg-input-synaptics in Ubuntu. https://bugs.launchpad.net/bugs/825548 Title: Touchpad cursor moves twice as fast horizontally after connecting an external monitor To manage notifications about this bug go to: https://bugs.launchpad.net/xserver-xorg-input-synaptics/+bug/825548/+subscriptions _______________________________________________ Mailing list: https://launchpad.net/~ubuntu-x-swat Post to : ubuntu-x-swat@lists.launchpad.net Unsubscribe : https://launchpad.net/~ubuntu-x-swat More help : https://help.launchpad.net/ListHelp
