normal rectangle:
rounded corner rectangle:
or
Here's the block:
effect:
Very good effort on your project. 
good job!
Wow! That's really useful. I'll think about adding it to Jens's button-making library. (That's where it belongs, don't you think?)
Did you work out the math? It's impressive even before seeing it on a computer. Do you understand the abrupt jump between effect numbers 14 and 15?
I diffidently suggest that the computation of Y might be a subprocedure, just because it would make it clear to someone reading your code that that part of the computation is the same in all four cases.
Also, this procedure has seven inputs, which is a lot. I'm not sure that the FILL input is very helpful; the user can put a FILL block in their script if they want, and also, that would give them the flexibility to choose a fill color different from the border color. (I know, they can just leave the input at its default False value. So this isn't a major issue.) And the same is true of the pensize input; the user can set the pen size before calling your procedure.
No!!!! check this link
formula for number 15..... X^2 + Y^2 = R^2 (circle formula)(R=radius))
formula for number 14..... X^4 + Y^4 = R^4
...
formula for number 11..... X^30 + Y^30 = R^30
a perfect square: X^infinity + Y^infinity = R^infinity
Where can I find this library?
It's called "Text costumes," the third entry in the second batch of libraries.
This is very good! If it doesn’t go in Jen’s library it should be in a library.
ok i was looking for a button library...
Well, buttons are the main reason anyone uses it! :~)
Another great use for it is to center text