Seems like the vlayer/blend painting doesn't work as it should in this release.
Before (1.5 and prior), when you set the ground with a vlayer, and used blend painting, one could simply hold the mouse1 and paint all around the desired vlayer area.
Now, that doesn't happen anymore.
Instead of painting like always, by holding the button, it just gives a small "tick".
What it means, is that you need to keep clicking really fast to paint an entire área, instead of holding, so it takes quite a while, depending on the map.