In the latest full release (1.8.4) double clicking seems to suddenly be recognised as a thing by the program - even though double clicking with the node tool doesn't actually do anything.
Usage / reproduce: Make a line with the pen tool, switch to node tool (a), click to add a new point, then immediately click again to start dragging it. In 1.8.3 this works perfectly; in 1.8.4 it stops dead without dragging. If I do the same clicks slowly, it works as normal. Same with clicking to select an existing node and immediately clicking again to move it (although in that case you can just click and drag in one motion, the behaviour has still changed.)
I couldn't see anything about it in the release notes or settings, but I may just be blind. Seems like a bug, or at least a change that's made it unusable for me, so I dropped back to 1.8.3 for now.