OpenGL/ C program that draws a polygon

need a program that allows the user to draw a 2D polygon in an OpenGl window, using the mouse then to draw an other polygon with a different color on top of the previous one, to play the role of a hole. The user should also be able to moved/drag the polygon, with the mouse, if he clicked inside the polygon and not on the hole.

This needs to be programmed in C not C++