geomview mouse functions for NeXT and SGI

[burchard]

Tamara, Dan, and I discussed how to resolve the differences in mouse  
model between SGI and NeXTSTEP for the purposes of Geomview.  Here is  
what we came up with.

The SGI version of Geomview uses mouse buttons and modifier keys as  
follows:
	Left				main function for mode
	Middle				variant function for mode
	Right				picking

	Shift				"slow" version of function

NOTE: The SGI version should *not* usurp any additional modifier keys  
in the future.

The NeXTSTEP version will offer *two* ways to access the same set of  
function variations.  The first column indicates NeXT-style  
modifiers, which are pressed in combination with the major mouse  
button (could be either left or right according to user preference).   
The second column is intended for SGI refugees:

	---		major button	main function for mode
	Alternate	both buttons	variant function for mode
	Control		minor button	picking
	Shift		Shift		"slow" version of function

NOTE: Shift may be combined with the other modifiers; Alternate and  
Control don't mix (this combination actually triggers  
context-sensitive Help).  There is a possibility that Alternate  
should be replaced by Command, in order to work better with the  
NS/Intel keyboard layout.

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Paul Burchard	<burchard at geom.umn.edu>
``I'm still learning how to count backwards from infinity...''
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