joining segments and highlighting regions

[Antonis Tsolomitis <atsol aegean gr>]

Hello,

Is there a way to join two segments so that they behave as a polygonal line?
Is it possible to do the same with a line segment and a bezier curve? 
Two bezier curves?

And is there a way to highlight a region? Say, I have a function (drawn 
with bezier curves)
and I want to highlight the region between the function, the x-axis and 
two lines x=a and x=b.
Can this be done easiliy somehow? Are there any plans for adding such 
functionality in the future?
I do not want something very fancy. Simple things like, day, shading 
with diagonal lines similar to xfig.


thank you,

Antonis.