Draws a rectangle with the specified Brush and Pen.
void DrawRectangle(IBrush brush, IPen pen, RoundedRect rect, BoxShadows boxShadows = default(BoxShadows))
The brush and the pen can both be null. If the brush is null, then no fill is performed. If the pen is null, then no stoke is performed. If both the pen and the brush are null, then the drawing is not visible.