Making a slider in openGL

Hey I’m a complete openGL noob. I’m attempting to make a simple slider. I have the following:

void display(){

    glClear(GL_COLOR_BUFFER_BIT);
    glLineWidth((GLfloat)2);
    glColor3f(0, 0, 0);

    glBegin(GL_LINES);

    glVertex2i(100, (height - 50 - 255));
    glVertex2i(100, (height - 50));
    glEnd();

    glBegin(GL_QUADS);

    glColor3f(1, 0, 0);

    glVertex2i(90, redY - 5);
    glVertex2i(90, redY + 5);
    glVertex2i(110, redY + 5);
    glVertex2i(110, redY - 5);

    glEnd();
    glutSwapBuffers();
}

void mouse(int button, int state, int x, int y){
    switch (button){
    case GLUT_LEFT_BUTTON:
        if (state == GLUT_DOWN){
            if (x >= 90 && x <= 110 && y >= redY - 5 && y <= redY + 5){
                ruberbanding = true;
            }
        }
        else if (state == GLUT_UP){
            ruberbanding = false;
        }
        glutPostRedisplay();
    }
}

void motion(int x, int y){
    if (ruberbanding && y <= 555 && y >= 255){
        redY = y;
        glutPostRedisplay();
    }
}

the display function is listed as my display callback. Why doesn’t this work? I think I may have misunderstood something along the way.

the window is only of size [-1; +1] x [-1; +1]
i think your vertex coordinates are too high