Since D3284 was inactive for a long time, I figured I could finish this. This revision also gives warning when there are no selected faces or when selected faces are invalid. Changes from reviewer (Dalai Felinto) : * Code style * Fix checking for ngons (BM_ITER_MESH is a for loop, you need to break from it before continuing the object iteration loop). Differential Revision: https://developer.blender.org/D3659