Here's a doozy: I often select a couple (non-sequential) messages to file away by Ctrl-clicking on them and dragging the messages into a folder. Most of the time this works as expected, but sporadically the messages in-between the ones I've selected are also moved!

This means I can't trust the drag and drop operation to move multiple messages. Ironically, I started noticing this because I habitually leave the messages in my inbox as unread (see previous post) and I was starting to see unread messages in my folders. (I only mark my messages as read immediately before I drag and drop them into a folder.)

I can't even entirely trust dragging and dropping a single message. If a new message arrives while I'm in the middle of a drag and drop operation, the wrong message is moved.