Extend surface only gives choice of extension factor, dragging to location fails

Hi,
V5
Having to work out an extension factor for extending a planar surface, why not have it with an option for planar surfaces extend from click start (the surface edge of course) to click extension point ?

How does one calculate an extension factor, new length divided by old length ?

I end up reaching for scale1D due to easier use for such.

Steve

Over here, selecting the edge to be extended, followed by a click on the point of the edge where to extend from (e.g. mid snapping), and then clicking somewhere else seems to work.