im new to qwt

i want to draw a grid in qwt, where it will look like a Rect (x1,y1, x2,y2, x3,y3,x4,y4) ... then i want to rotate it with a specific angle.

so can anybody please help how can we rotate items in qwt is there any function such as QRect.rotate ("angle").
and is the there a Rect item in qwt or i have to draw each line by it self.