Clipping Mask

At the moment you can create a an empty mask or mask layer content. Pleae note that you canot make a mask to a vector layer.you can copy and paste a mask as well. 

here are sample screen shots for masking. I created a simple brush splash.

Simple drawing.

Next shot will be creating a simple mask.

Left side creating the empty mask right image drawing on a mask. Black Coneals Whire Reveals.

Drawing not on the mask.....adding pixels....

This one is mask layer content..as you see you can see the mask and draw on it!

Hope it helps!!!