You know, I'm a drummer, and despite all the snarky jokes about drummers can't read any music that's not on a straight line, I do respect my other musical peers need for reading key sigs, and distinguishing between minor, and Major sigs.  It's kind of like ignoring the time sig 2/4, and just using 4/4, since all you need to do is add 2 of them, and you've got 4/4.  So, why does Sonar ignore minor key sigs.  Or, at the very least, allow a user to add them to an .INI file if, and when they need them?  That's all I got to say 'bout that!
 
KC

I've wondered about that also. But since every minor key has the same key signature as its relative major, you can get by ok as long as you keep a chart handy showing all the major and minor pairs. For example, C Major is the same A Minor. The Circle Of Fifths is one such chart. It's also neat as you can see how far away from each other the various keys are. 

What he said^^^^^
 
The key sigs of the relative pairs is exactly the same....
 
C major relative to A minor .... no sharps or flats on the staff.
G major relative to E minor   one sharp F#
 
and so on

This was all covered here, in his duplicate post
 
http://forum.cakewalk.com/Key-Sigs-for-minor-Keys-m2905947.aspx