You can select the trimming area with drag & drop.
Trimming:
Rectangle
Square
Circle
Draw
Trimming
Geometry:Sphere
Geometry:Box
Face:Single
Face:Single(reverse)
Face:Double
Face:Double(reverse)
Face:None
Max:16px
Max:24px
Max:32px
Max:48px
Max:64px
Max:80px
Max:96px
Max:112px
Max:128px
Redraw
Make X3D