Virtual member functions

• virtual int is_menu(void) - return whether this object is an on-screen menu form, or another type.
• virtual int is_on(void) - return whether the object is currently active.
• virtual void On(void) - turn on the UIObject.
• virtual void Off(void) - turn off the UIObject.
• virtual void move(int, int) - moves the UIObject the the given X,Y position on the screen, where X and Y are in pixels measured from the lower-left corner of the display. This may not be applicable to all UIObject's, if not is is ignorned.
• virtual void where(int &, int &) - return the position of the UIObject, if applicable.
• virtual void init(void) - initialize the user interface. This is called once at the beginning of VMD, after all the UIObjects have been created.
• virtual void reset(void) - resets the user interface object, forcing an update of all the informative displays, etc.
• virtual void update(void) - updates the display, for example for some visual items which much change each time the scene is redrawn. This is called in the main loop of VMD after all queued Commands have been executed, before the scene is actually rendered.
• virtual int act_on_command(int, Command *, int) - this is called after a command is executed, and it is seen that this UIObject is interested in that command. The first argument is the command code, the second the Command itself, and the third is the success of the command. This routine should check what the code is, and based on that update any visual or other such representation of the program to reflect the change caused by execution of the given command. Returns TRUE if this UIObject actually did something due to this command being executed.
• virtual int check_event(void) - checks whatever external interface is necessary to see if a new command from the user has been entered. If so, this routine creates a new Command object, and adds it to the queue.