I have just fresh installed 12.04, there were a handful of packages that were upgraded right away (12 or so). Aside from that I haven't tweaked or installed anything else.
I have gone into my System Settings -> Appearance -> Behavior tab and turned on Auto-hide the launcher.
At this point placing my mouse cursor to the far left edge of the screen should open my launcher. Here is a short video showing you what is happening.
http://www.youtube.com/watch?v=shMSEJT61aM
I have tried setting the Reveal Sensitivity all the way to low, and all the way to high and it still appears the same for me.
you will also notice in the video that there is a small dropshadow that appears on the edge of the screen when (imo) the sidebar should appear.
Is there a configuration I am missing? does Reveal Sensitivity not do what I would assume it does? Any help would be appreciated.
Just to let you know in this thread how I solved the problem (according to the linked answers).
The lower the figure, the more sensitive the launcher will be, and the easier it will appear.
Problem solved! =) A note to the Ubuntu guys, the slider in the system settings should go from 0 to X, so you can actually remove the pressure alltogether. The default settings are extremely annoying on an Macbook Air with a mouse pad.
Hope I can save you all some clicks.