Date:	Wed, 4 Dec 1996 09:27:11 GMT
From:	kvhk AT ivs4 DOT barco DOT com (Koen Van Herck)
Message-Id:	<9612040927.AA24095@ivs4.>
To:	djgpp AT delorie DOT com
Subject:	JPTUI callback function
Reply-To:	Koen DOT VanHerck AT barco DOT com

I also have a problem with the callback functions. I want to make a
checkbox which is checked, but cannot be unchecked. (without being disabled).
I made a callback function to undo an uncheck action.

void undo_uncheck(PCheckBox pcb, char *arg)
{ 
  pcb->m.check();
}

MyCheckBox.m_set_unchecked_callback(undo_uncheck, "");

Now the compiler generates an error or warning because I should use
PObject instead of PCheckBox. But if I do that, I cannot use CheckBox
methods in my callback function. How should I do this ?

Is it allowed to put a 0 instead of the "" ? 

What happens with the string argument ? You do not declare it as
const, so I cannot use a const char * for this ? Why not ?

Maybe there is a better way to achieve what I want. All comments are
welcome. 

----
Koen Van Herck
Electronic Design Engineer
E-mail: Koen DOT VanHerck AT barco DOT com

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