Tool Palette control create modes
selection handles for selecting and moving
growing disabled for bitmaps
moving and growing disabled for lines
constraints keep lines attached to bitmaps
all operations are undoable
multiple undo
menubar for commands
supported operations are: quit, undo, redo, cut, copy, paste, clear, clear-all,
	select-all, to-top, to-bottom
command hierarchies used for appl-specific extra work to cut lines when 
	cut object
gridding for object placement and moving
can only attach lines where appropriate--depends on object type and where 
	cursor released on object
computes the value of the circuit 
animations on when change values
gestures for defining all objects
	o=or, A(onestroke)=and, >=not, dot=undo, line=line, L=onezero,
	? (no dot) = output

NOT selective undo == too hard to implement

