Comment 5 for bug 262305

The only recent change that I can see in this area is that the Synaptics driver will now respect what the hardware tells it about the widths of the edges. Previously it had hardcoded defaults that were used regardless of what the hardware said.

You can try to adjust them with the xinput command line program. The "Synaptics Edges" property of the touchpad lets one customise the same options as {Left,Right,Top,Bottom}Edge, but without having to restart X or obtain root privileges.