@aerilius said:
I've done similar experiments and found evidence that Threads do (partially) work.
And ... in PC SketchUp prior to v8, it distro'd with Ruby v1.8.0 in which the Thread class was very unstable.
But threads have gotten more stable in Ruby versions above v1.8.6, even more so in the v1.8.7 branch.
Keep in mind that all the Mac Sketchup editions still disto with Ruby v1.8.5 (initial release.)
Usually .. coders wish to use threads in order to prevent SketchUp from blocking.
As ThomThom said.. threads in the Ruby 1.8.x trunk are green threads (still within SketchUp's process.) Read the description of Green Threads at wikipedia.
DITTO what TIG said.