opengl program->"Free hand drawing with mousse"

#include<GL/glut.h>
#include<stdlib.h>
#include<time.h>

const int screenWidth=640;
const int screenHeight=480;


void myInit()
{
     glClearColor(1.0,1.0,1.0,0.0);
     glColor3f(1.0,0.0,0.0);
     glPointSize(1.0);
     glMatrixMode(GL_PROJECTION);
     glLoadIdentity();
     gluOrtho2D(0.0,(GLdouble)screenWidth,0.0,(GLdouble)screenHeight);

    
     }
    
    
     void myDisplay()
     {
          glClear(GL_COLOR_BUFFER_BIT);
          //glFlush();
          }
         
         
          void myMouse(int button,int state,int x,int y)
          {
               if(button==GLUT_RIGHT_BUTTON)glClear(GL_COLOR_BUFFER_BIT);
//               glClear(GL_COLOR_BUFFER_BIT);
               }
         
          void myMovedMouse(int mouseX,int mouseY)
          {
               GLint x=mouseX;
               GLint y=screenHeight-mouseY;
               GLint brushsize=15;
              
               glRecti(x,y,x+brushsize,y+brushsize);
         
               glFlush();
               glEnd();
               }
         
    
    
void
mymenu(int value)
 {    
if(value == 1)
{
         glRecti(0,0,50,50);
         glFlush();
                  }
                 
if(value == 2)
{
         glBegin(GL_LINES);
         glVertex2i(0,0);
         glVertex2i(100,100);
         glEnd();
         glFlush();
         }
}
    
         

    
     int main(int argc, char **argv)
     {
        
         int k=0;
         glutInit(&argc,argv);
         glutInitDisplayMode(GLUT_SINGLE | GLUT_RGB);
         glutInitWindowSize(screenWidth,screenHeight);
         glutCreateWindow("mouse cliks");
         glutDisplayFunc(myDisplay);
         glutMouseFunc(myMouse);
         glutMotionFunc(myMovedMouse);
        
         k=glutCreateMenu(mymenu); // single menu, no need for id
          //glutAddSubMenu ("raj", k);
          //glutAddSubMenu ("j", k);

         glutAddMenuEntry("Rectangle", 1);       
         glutAddMenuEntry("line", 2);
         glutAttachMenu(GLUT_RIGHT_BUTTON);
      
         myInit();
        
         glutMainLoop();
         }