Here's a topic I've written with practical info about the WebDialog class: http://forums.sketchucation.com/viewtopic.php?f=180&t=23445#p198883

Sketchup uses inches, but provides methods so you can use any measure you like -> http://code.google.com/apis/sketchup/docs/ourdoc/numeric.html

val = 1.m # 1 meter pt1 = [0,0,0] pt2 = [val,0,0] pt3 = [val,val,0] pt4 = [0,val,0] my_face = entities.add_face [pt1, pt2, pt3, pt4]

Sorry about the typo !
I've corrected the original post 😳
[== a brain-fart - I must must type 'module' several times a day !]

Pls move to Developers forum.