When the pointer focus is on the canvas (where the graph is drawn), there 
are some shortcuts to activate several actions. They are:
	-   ^A - autoscale plot
	
-   ^B - draw a box (using the current settings for boxes)
	
-   ^D - delete an object (string, line, or box)
	
-   ^N - move an object (string, line, or box)
	
-   ^P - draw a line (using the current settings for lines)
	
-   ^V - set the viewport with the mouse
	
-   ^W - write a string (using the current settings for strings)
	
-   ^X - exit (abruptly) xmgr.
	
-   ^Z - enable zoom