libgtkextra for plotting?

[rulomanic]

I would like to have some 2d plots in my app, 3d if possible in near future.
I have my Ubuntu Dapper, with Anjuta and Glade installed via synaptic. So, looking for some plot library I reach to libgtkextra, but once installed I don't get the widgets at Glade's widgets palette. What would be the problem? Is there a solution? an alterative aproach to 2d plot?
Thanks a lot in advance.

[hod139]

For an alternative, I've alwaysed used gnuplot (http://www.gnuplot.info/) for generating all my plots.

Edit: I didn't really read your post very carefully. I've never tried calling gnuplot from a application to generate plots. I've only used it as a stand-alone application. I'm no longer certain if it is a viable alternative for you.