Future Layerbox

[Sven Langkamp]

Just saw Boudwijn's quote on #107348

> [19:56] <_boud> So, to the user it would like you could add a number of 
persistent selections to your layer, and every persistent selection has an 
associated effect. 
Such a persistent selection could also be added to a layer group.

> [20:12] <_boud> bcoppens: basically, we need something that can: show a 
preview, show a configurable amount of bools per layer with specific icons, 
arrange layers in a hierarchy, rearrange layers with drag and drop and remove 
and add new layers. It cannot be hard, but it would have to have an api 
that's usable without depending on any app-specific class. 

I think the layers could be organized as a tree. Something like:

Image
\
+ Layer 1
+ Layergroup bla
   \
   + Layer 2
   + Layer 3
      \ Selection -> Blur
   + Filter Round Corners

In Karbon objects and groups of objects are displayed as part of the layer. So 
the new layerbox should be able to display them too.

If possible the new layerbox should use the new Model/View architecture 
introduced with Qt4.

Just wanted to add some complexity ;)