Interactive regression on a plot

Perform regression on plotted data in a figure by manually choosing the regression area.

Plot data in a figure, and then interactively choose regression area. The result from polyfit is returned.
Example:
x=1:1:10;y=sin(x);
f=figure; plot( x,y );
[p,h] = figreg( f, 2 );
%fit a second order polynom to selected region in plot