Make weight paint gradients respect locked vertex groups

I love the idea of the gradient tool for painting weights, but it's kind of a bummer that it paints over vertex groups that have already been polished and locked.

Unless I'm really missing something, the only current alternative seems to be to use a large brush with 2D projection on instead, which is several more clicks than just dragging out a gradient in one sweep.

It would be nice if there was a setting or something that forces it to only affect unlocked vertex groups.

Thank you!