struct control_data
{
    // declare some data that you want to have associated with your control.
    CDATA color;
    _32 last_buttons; // used to track when a click happens
};
   
EasyRegisterControl( WIDE( "simple" ), sizeof( struct ball_timer_data ) );
   
// define the function called when a new 'simple' control is created.
static int OnCreateCommon( WIDE( "simple" ) )( PSI_CONTROL pc )
{
    MyValidatedControlData( struct control_data*, my_data, pc );
    if( my_data )
    {
        // assign a color to start
        my_data->color = BASE_COLOR_RED;
        return 1;
    }
    return 0;
}
   
// define a method to draw the control
static int OnDrawCommon( WIDE( "simple" ) )( PSI_CONTROL pc )
{
    MyValidatedControlData( struct control_data*, my_data, pc );
    if( my_data )
    {
        Image image = GetControlSufrace( pc );
        BlatColor( image, my_data->color );
        return 1;  // return that the draw happened.
    }
    return 0;  // return no draw - prevents update.
}
   
// define a handler when the simple control is clicked.
static int OnMouseCommon( WIDE( "simple" ) )( PSI_CONTROL pc, S_32 x, S_32 y, _32 b )
{

    MyValidatedControlData( struct control_data*, my_data, pc );
    // this checks to see if any mouse button goes down
    if( MAKE_NEWBUTTON( b, my_data->last_buttons ) )
    {
        if( my_data->color == BASE_COLOR_RED )
            my_data->color = BASE_COLOR_GREEN;
        else
            my_data->color = BASE_COLOR_RED;
        // tell the control to update.
        SmudgeCommon( pc );
    }
    // save this button state as the prior button state for future checks
    my_data->last_buttons = b;

}