In ArtRage Studio and ArtRage Studio Pro we changed the way canvas colour and layers interact. In ArtRage 2.5 every layer could have different paper colour. However we found that causes some serious work-flow issues when you're trying to combine layers with effects such as watercolour. It also didn't work very well with exporting layers with paper colour to Photoshop PSDs.
So in ArtRage Studio and ArtRage Studio Pro we separated out the paper colour, and made it a 'virtual layer'. When you export to a PSD that virtual paper layer becomes a physical PSD layer. If you then import the PSD back into ArtRage, the PSD layer is still a real layer, but the virtual paper layer no longer exists - it has transparent paper. Which means the *next* time you export to a PSD you dont get yet another layer.
This means the overall look of the document (layers against paper) is preserved when you export to a PSD, but all the transparent paint layers are still editable as transparent layers.
If you dont want the PSD exported with a white base layer, just set your paper colour in ArtRage to transparent. No paper layer will be exported in that case.
AndyRage's mantra for graphics engine code:
"Sure - how hard can it be?"