Re: communicate data between GUI

I've another problem using callback for data excange:

Now I can communicate between GUI_1 ( contains a text box) and
GUI_toggleButton ( contains the 'model'
But I doesn't undestand the role of the parameters

----------------------------------------------------------
IN GUI_1

function val_1_Callback
....
GUI_toggleButton('test_cb',0,value);
% The first parameter is the name of the callback in GUI_toggleButton
% The Third parameter is the passing value
% What is the second parameter?If I put another value different to
zero, it doesn't work
---------------------------------------------------------
IN GUI_toggleButton

function test_cb(tmp,val )
disp( 'new value is:')
disp(val)

%The first parameter is the 0 value - I don't understand it
% the second is the value that I want to use

-------------------------------------------------------------

Someone could send me a suggest, or a link or keyword for the Matlab
documentation?

Thanks !

.