Layers for drawings

Hello, 

It would be nice to be able to organise drawing-elements into layers (something like photoshop or any other (a litle advanced) drawing tool can). When these layers have the possibility to be set to visible/invible you can show/hide multiple drawing-elements at once. When doing your analysis you can add each type of analysis into a layer, hide it and do the next type of analysis. Later on you can show all layers and see the full result.