Fix for crop tool crash

[Boudewijn Rempt]

On Mon, 24 Aug 2009, Cyrille Berger wrote:

> Hi,
> 
> We discussed this on IRC. Here is the conclusion:
> * paintdevice colorspaces belongs to the paintdevice, therefor they have a 
> short/unpredictable life expectency, you should only use them as long as you 
> are certain that the paintdevice won't be deleted
> * if you need to keep a pointer of the color space (like in a KoColor), you 
> need to ask the KoColorSpaceRegistry for a permanent colorspace (see the 
> permanentColorspace function)
> 
> In this case, since it's a property of the layer. Storing the id/name in the 
> model would be the way to go.

I don't get this last bit -- can you unpack a bit?

Boudewijn