How to achieve drawing a simple rectangle?

[slobodanantonijevic]

So I'd like to have a simple rectangle drawn instead the rounded corners one.
I am having trouble in finding any method to do this, and also tried to extend the TutoShowcase proved to be a hellish task, as its construction is almost non-extendable.

So is there any simple way other than actually downloading and manually changing the lib my self, which I'd like to avoid if possible.

Cheers