Enable/disable touchpad

I'm running Fedora-22/KDE on my ThinkPad T510. Ctrl-Y turns off the touchpad on this laptop. But this only works until the next re-boot. In System Settings=>Hardware=>Input Devices=>Touchpad there is an option "Enable/Disable Touchpad" which I assume is meant to toggle the touchpad on and off. On my machine it seems to have no effect. Have I misunderstood its purpose? Or does one have to install some other package for it to work? As I recall, there was a straightforward option "Disable touchpad" in Fedora-21/KDE, which worked perfectly. -- Timothy Murphy gayleard /at/ eircom.net School of Mathematics, Trinity College, Dublin