In the experience I had with ViaCad on the Mac in the last two months, I wrote down some suggestions for improvement. Hope you can use this.

Layers: You should be able to move a layer by dragging them with the mouse. It doesn't make sense the layer title gets a black bar, but you can't do anything with it.
Layers: Why not use the black selection bar as the active work layer? The layer window can become smaller then as well.
Layers: In my opinion, it should be possible to make a layer invisible, even though it's selected as the work layer.
Layers: Create new layer above or under currently selected layer, not at the bottom of the layer list.
Layers: Should be able to toggle active layer, to quickly check difference. So remove delay of layer on/off.
Layers: Command-A doesn't work when cursor is active in Layer title, to select the whole word.

General: Command-D for Don't Save in the pop up window doesn't work
Snaps: Temporary turn snap off when dragging a curve, by pushing the command key fx.

Suspending snaps temporarily would be very nice.
Also agree about the Cmd D bug. That's important.