C++, Opengl - How to draw How to draw square on the button at the center? : How to draw a square on the button at the center (like stop button)? 
In this code that I try it be like a rectangle and full of the button.
How can I solve this problem?


[This is my code.][2]
[This is my code.][3]

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    void ButtonDraw(Button *b)
        {
        	if(b)
        	{
        		/*
        		 *	We will indicate that the mouse cursor is over the button by changing its
        		 *	colour.
        		 */
        		if (b->highlighted) 
        			glColor3f(0.7f,0.7f,0.8f);
        		else 
        			glColor3f(0.6f,0.6f,0.6f);
        		/*
        		 *	draw background for the button.
        		 */
        		glBegin(GL_QUADS);
        			glVertex2i( b->x     , b->y      );
        			glVertex2i( b->x     , b->y+b->h );
        			glVertex2i( b->x+b->w, b->y+b->h );
        			glVertex2i( b->x+b->w, b->y      );
        		glEnd();

               /*draw red square on the button*/
        		glBegin(GL_QUADS);
        		glColor3f(1.0f, 0.0f, 0.0f);
        		glVertex2i(b->x, b->y);
        		glVertex2i(b->x+b->w, b->y);
        		glVertex2i(b->x+b->w, b->y + b->h);
        		glVertex2i(b->x, b->y + b->h);
        		glEnd();

        		/*
        		 *	Draw an outline around the button with width 3
        		 */
        		glLineWidth(3);

        		
        	}
        }


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  [2]: https://i.stack.imgur.com/bYeeR.png
  [3]: https://i.stack.imgur.com/aEQJF.png