User Button Gadget:       

  This gadget places buttons on your diagrams.  The buttons 
  become active during simulations.  When pressed, the buttons call
  your designated functions.  To place such a button in a diagram,
  instantiate a model in your diagram that contains the following
  function call:

	user_button( label, x, y, your_function, your_data );

  The label is a character string containing the word you wish
  to appear on the button, (ie. "on", "off").  

  The x and y values are the floating-point coordinate 
  offsets where you want to place the button on your diagram relative 
  to the box under which it is instantiated.  An x-y value of (0.0,0.0) 
  will place the button at the upper left corner of the box where it is 
  instantiated.

  The your_function is the name of the function that you want
  to be called when the button gets pressed.  You should define this
  function within a DEFINE_GLOBAL: area.

  The your_data is any data item or a pointer to a structure
  that you wish to pass to your called routine.  For example, this
  could be used to determine which of several buttons was pressed.


  For example:

	DEFINE_GLOBAL:

	 /* Prototype the standard function. */
	 void user_button( char *label, float x, float y, 
			   void *u_func, int data_arg );

	 /* Define your (user) function. */
	 void user_test( Widget w, caddr_t client_data )
	  {
	   printf("Button Pressed %d\n", client_data);
	  }

	END_DEFINE_GLOBAL.


	/* Define your box-model that contains some buttons. */
	DEFINE_DEVICE_TYPE:  Button_Box

	  DEFINE_THREAD: start_up
	  {
	   user_button( "Here", 0.1, 0.1, user_test, 10 );
	   user_button( "There", 0.1, 0.4, user_test, 20 );
	  }
	 END_DEFINE_THREAD.

	END_DEFINE_DEVICE_TYPE.


  To try this example, you would create a diagram that instantiates
  a box of type Button_Box.  If you built and ran the simulation
  containing this example-model, you will see two buttons appear
  on the box;  one below the other, due to the y-offsets of 0.1 and 0.4.
  The labels on the buttons would be: Here and There.

  If you click the first button, it will call the function user_test
  which will print:
	
	Button Pressed 10
	
  in the text window, reflecting the value 10 being passed to it.

  If you click the second button, it will call the function user_test
  which will print:
        
        Button Pressed 20
       
  in the text window, again, reflecting the value 20 being passed to it.

  You can establish any number of buttons, and they can call any number
  of functions that you define.

General Purpose Button Box Model -

As a convenience, there is a general purpose pre-built button model in the user contributed models library. The model has one button and one output port. Whenever the button is pressed, it outputs a one on its output link. You can instantiate any number of these button-boxes in your diagrams. The button label takes the instance name of the box.
To use, simply import:
        $CSIM_MODEL_LIBS/user_contributed/generic_button.sim
Then instantiate boxes of type:   button_ctrl

There is a complete example in the user_contributed models directory, called generic_button_example.sim. It instantiates four buttons with test boxes. Pressing a button lights the box it is connected to. Try it by building and running it.