Quite a basic question: I've noticed that to show the launcher when it's hidden that I have to move the mouse to the top left of the screen, rather than simply move the mouse to the left edge of the screen. Is this a bug or is it like this by design? If so, is there a way to make it show when the mouse is at the edge?
Secondly, is it possible to prevent the launcher from only coming half into view if the mouse is moved slowly over the menu button? Sometimes I want to show the launcher but I've moved the mouse too slowly (usually because the pointer was already in the vicinity).
Recently the behavior has been changed so that pushing your mouse towards the left edge of the screen reveals the launcher.
Pressing and holding the Super key (Windows logo) will also reveal the launcher. Also (while you're at it) you can press Super plus any number to activate the corresponding launcher (i.e. launch the application)
Yes it's by design that you move to the top corner rather than just the side.
As for your second question, I find that very frustrating. It's not just about the speed, what you need to do is to push the mouse into the very corner of the screen. As far as it can go, not just over the button. I reported a bug about this, though it won't be fixed before 11.04's release.
As an alternative, to avoid both your problems, if you have a largish screen, you could set the launcher to never hide.
The trick is to make a semi-loop around the logo - move it into the corner and then move it down. Then the launcher comes up okay.
I personally found this behavior very easy to work with once I got it, and the launcher doens't open when I don't want it to either.