Switch between Perspective and Orthographic projection.
Up X/Y/Z/-
Select the "Up" axis for the loaded mesh. By default its Z-up, which is standard among CAD applications, but many popular animation programs use Y-up. So if you load your mesh and its lying on its side, try the Y-up or X-up options to get it up the right way. The "-" option turns on free rotation; UVLayout won't try and keep the object upright, and so you can tumble the view beyond the normal camera lock points.
Light Slider
Move the slider to move the light source from right to left.
View UV/Ed/3D
Switch between UV edit, 3D edit and 3D textured views. Use the ? hotkey to find out what other hotkeys are available in each mode.
Color Error/&/Relax
Switch between "flattening error" and "relax weight" coloring of polys when in the UV view. Use the "&" option to blend the two coloring schemes.
Trace
Select Trace to load an image in the background when editing UVs. Use the first slider to fade the background in and out, and the second slider to change the transparency of the flattened geometry. Select Trace a second time to turn the background image off.
