The one feature I still really miss from PS is the ability to OPT+Click on a layer mask and see it in BW while having the ability to edit it with any tools, just like any other bitmap layer. For example, I sometimes modify my layer mask with level adjustments or other manual edits to the mask that are not present in the otherwise wonderful "edit mask" function in Pixelmator.
I've found a workaround: copying the mask, pasting it as a regular bitmap layer, making the edits, and then reapplying it to the target layer, but this is definitely a bit clunky.
It seems like it's a simple thing to add, but I am no engineer.
