It's great when it works like that.
I would think that it's actually the correction of a bug. Like you, I'd always double clicked but I think that should only be necessary to go to another layer and a single click to select the layer.
It will help others if you could please edit your OP and add [Solved] to the title.
Self-righteousness is a loud din raised to drown the voice of guilt within us - Eric Hoffer
Don't believe what it says on the right - I am anything but sagely; More oniony!