http://forums.tigsource.com/index.php?topic=2916.0
Home, sweet Home! This is the interface you'll have for most of the time. As a rule of thumb, left mouse button (LMB) will do standard actions, while right mouse button (RMB) will go into relevant setup/option interface of some sort. For example, LMB on the Zoom button will let you select an area to zoom into. RMB on the Zoom button will allow to to pick the degree of zoom. So, if you use the LMB in the open area, you will draw with the selected tools. RMB will hide and show the Home frame. You can also use "Space" for this. Oh, and if you ever get stuck in an interface bit where you want to exit, you can just RMB over the open area, or press "Space".
Now, onto the specifics!