[chlor-develop] Delete-Operation and Z-Ordering

[<chl...@li...>]

Hi,

I was quickly thinking on implementing the delete operation and the  
consequences of making this operation undo-able.

Alas, using the add operation as the inverse of the remove operation  
on a mutable array isn't correct, as we would loose the z-ordering  
during drawing (e.g. removing the first drawn object, hitting undo  
and adding it at the end of the array makes it the last object being  
drawn and thus the topmost, right?).

Okay, how in general should we go for z-ordering? Shall we use the  
array position within CLayer implicitly as the z-order? Shall the z- 
order work across layers? Shall every CObject carry its own z-order  
then as a third coordinate?

Any opinions for this sort-of-requirements-elicitation?

Regards,
	Florian