How do you unsplit a split task?
 

How do you merge a task that was manually split into two, back into one task.

It is not obvious how to do it from the GUI and the online help did not help.

To the left of the task name there is a disclosure triangle. Click it to open the split task. Select all the pieces inside, and delete them as a group.

That approach will more or less turn the task you are unsplitting back into a copy of the "prototype task", that is, it will look just like a new task. If you have changed the duration for ecxample, that will be lost.

Instead, just drag the pieces until they touch and they will merge.

-Tom

Ah, so it will. Of course, you can't actually drag the pieces until they touch — it still shows a gap at closest approach. Not the most discoverable behavior as a result, and like the OP says, nothing in the documentation. Seem to be some graphic rendering issues as well in the latest SP, I'll send in some feedback.