Missing ScreenSize & ScreenPixelsPerInch properties

[Ben Abbott]

In Matlab a "ScreenSize" property is available,

	get (0, 'ScreenSize')

If there are no objections I'd like to see a "ScreenSize" property  
added to "root" in Octave as well. As we have  no method to actually  
determine the size of the display, I'll suggest it be a *writable*  
property and set to some nominal default. The site below suggests  
1024x768 to be typical

	http://www.rochester.edu/IT/reports/graph/screenstat/screenchart.php

To allow this property to be used with various figure and axes  
"position" related properties the "ScreenPixelsPerInch" property is  
also needed.

	get (0, 'ScreenPixelsPerInch')

and again, I suggest this be a *writable* property and set to a  
nominal value (say 72).

If someone skilled in c/c++ can take care of this, I'm happy to do  
what I can to have the gnuplot backend respect the various properties  
impacted. The files I'm thinking of are gnuplot_drawnow,  
__go_draw_figure__, __go_draw_axes__, and some tweaks to subplot.

Ben