Hi, i might be faced with a similar problem too, i've been thinking about it, i've discovered you can set macro's to function when a user clicks on the shape, but i don't have the time to look into it yet, however in a few days i might have time, I did have a quick look however and...

...i've made a little spreadsheet, basically you enter the Length And Height, and it'l make a triangle, not sure if it'll be any use, its very hard to work out all these xy's on teh shapes i thought, but it made me think away from what i've been stuck on for the past few days!

it allso adds nice little double ended lines

I figured it may help build more complex shapes, theres also a nice button that rmoves all the lines on spreadsheet, which is very useful, as i was deleting all the lines manwelly for ages, well if its no use, i think its neat anyway!