Explaining Dia: green|red buttons

["loli" <loli unsa edu ar>]

Every  Dia's user knows about some green|black|red  buttons (or boxes or  
small square dots) appearing in a diagram when an object is selected. 
 
And sometimes, a  green button becomes  red  to indicate a "binding" between  
two objects: the green button occuppies the same place of a connection  
point.  
 
But not all red buttons indicate bindings. 
 
I propose that any green o red button change  to blue to indicate a binding  
has occured. I choose blue because blue is the already chosen color to  
display connection points. 
 
More detailed arguments in favor of the proposal: 
  
There is not a complete explanation about theese matters in the manual (and  
perhaps it is not needed for the general user: one learns faster by using a  
tool than by reading about it). 
  
But in order to produce an explanation .... 
I detected three situations about red buttons associated to different types  
of lines: (all of theese buttons are good to change the form of the line)  
 
1- red buttons which became green when moved to indicate a corresponding    
binding has been broken; and go back to red when a binding is made.  
Try, for example, 'line' and 'zigzagline'.  
 
2 - red buttons which never change color and cannot be binded to other  
objects. 
Try, for example, 'zigzagline' and 'arc'. 
 
3 - red buttons which never change color but can be binded to other objets.    
Try, for example, 'polylyne' or 'bezier' with at least two segments.  
--   
Loli  
loli unsa edu ar