Why don't you present a logical case for a solder paste layer?
I'm hopeful that Iliya will return to the forum. He has certainly worked hard at implementing many of Free Electrons suggestions ............ all within a very short time frame.
Now, to the solder paste screen. I will attempt to be constructive.
We should also be able to also choose different grids for the solder paste stencil.
The reason for this is that solder paste is now often used as a heat-sink for SMD components. To keep the rigidity of the solder paste stencil & to prevent the flux from forming bubbles in large areas of solder paste, we need to grid the solder paste on top of the exposed copper (no solder mask on the copper pour of course).
The mosfet heat-sinking is provided by the solder paste. To do this we:
1/ Place a polygon copper pour on the top layer;
2/ Open up the solder mask so that the copper remains exposed;
3/ Place "Gridded" solder paste on top of the exposed copper. When the board is run through the infra-red reflow oven, the solder paste will spread out, covering all the exposed copper. The mosfet now has fantastic cooling by the solder paste (often 2oz or 3oz copper is also chosen to aid with cooling) & the board is complete as soon as it comes out of the reflow oven. No heatsink to buy, no heatsink to install & no messing around with heat transfer paste.
I have uploaded an example below (completed manually in DipTrace as DipTrace does not auto-generate patterns on the solder paste mask layer - I have requested that they add this to their next upcoming version).
Notes:
Background is grey
Top copper layer is hidden
Top solder mask exclusion area is in pink
Top solder paste is in dark yellow. The grids were all painstakingly added manually.