I have the same problem with 15.04 on a Thinkpad Carbon X1. I found https://bugs.freedesktop.org/show_bug.cgi?id=55821 and confirmed that rmmod psmouse + modprobe psmouse seem to fix it.
https://bugs.freedesktop.org/show_bug.cgi?id=52496#c31 says it was fixed in recent versions of synaptics and point to the following commit for 1.7 branch: http://cgit.freedesktop.org/xorg/driver/xf86-input- synaptics/commit/?h=synaptics-1.7-branch&id=bbaf4d646ebf4393a1ee0eb9bcc569054ed878f9 Could 15.04 get an update with that patch? ** Bug watch added: freedesktop.org Bugzilla #55821 https://bugs.freedesktop.org/show_bug.cgi?id=55821 ** Bug watch added: freedesktop.org Bugzilla #52496 https://bugs.freedesktop.org/show_bug.cgi?id=52496 -- 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/1454473 Title: In Ubuntu 15.04, simply moving the mouse via touchpad scrolls the window To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/xserver-xorg-input-synaptics/+bug/1454473/+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