Thanks for the details about how you set angles in your sky textures.

Will there also be a vertical offset for wall textures?

The vertical Y offset is available for all textures except for the sky texture.

YGYL, the fact that a polyline is displayed in the 3D view is actually stored in an [font=courier new]elevation[/font] attribute which value can't be set in the user interface at this moment (but you can try it in the Home.xml entry), because I can't think of an application of a polyline with an elevation > 0 which would float in the air. Give me some real examples and I'll study them.