It might be a plugin clash, and until you've tested as Dave suggests we won't know... but I can't envisage any 3rd party code that might do this - so I suspect it's a Sketchup/OpenGL/graphics-card issue - have you tried reinstalling/repairing Sketchup ?

Glad it worked, but that's the only way I know of - if you do find another way, let us know!

oh. one of those.
yeah, you can't do it solely with standard sketchup inferencing.

i bet there are quite a few tricks out there but my own go to is similar to yours except i'd use TIG's extrude edge by vector to make the vertical face.. (select a line, extrude it up (or down) but keep it as a group for easy deletion when your done with it.. draw the vertical line then delete the group).

i guess if i had a lot of these on one drawing, i'd consider draping all the criss-cross lines (sandbox tools) onto a flat plane which would show you where the intersections are.

@wozabee said:

It works just absolutely spot-on now!!

...now to re-learn some Keyframe animation & such, and see if I can put this chap through his paces.

Thanks so much again Kwok!

Woz, you're welcome. Would love to see the animation, when you are done. ☀

BTW, here's the link to Kwok's "Key rotate" plug-in:

http://forums.sketchucation.com/viewtopic.php?t=28086

Thanks for the pointers so far Kwok!

Woz

Thank you, Thank you, Thank you, Thank you, Thank you, Thank you!!!

Hopefully... this'll solve my woes.

Cheers Honoluludesktop,

Woz