Re: Change Button Label

[Luciano Chavez <lnx1138 us ibm com>]

On Mon, 2002-10-07 at 08:08, Amit Jain wrote:
> 
> Hi All
>   I want to change label of a button.I got success in changing it but unable to understand the meaning of that particular line which is written below
>  GTK_LABEL(GTK_BIN(button)->child)
> Why should i first typecast button into GTK_BIN and again convert it into button from GTK_BIN(button)->child.
> I guess GTK_BIN(button)->child gives button object.am i right or doing some mistake in interpreting the meaning of it.
>

A GtkButton is a subclass of GtkBin. A GtkBin is a container subclass
that contains only one child object (pointed to by the child field). So
when you cast the button with GTK_BIN, you were doing this to access the
child object. The child of a button is typically a GtkLabel but does not
have to be. It could be a pixmap or a box containing a pixmap and a
label. Unless you're positive its a label, you may want to test the
child widget with a GTK_IS_LABEL(GTK_BIN(button)->child) before casting
it as GTK_LABEL just to avoid GTK warnings.
 
-- 
regards,

Luciano Chavez

lnx1138 us ibm com          
http://evms.sourceforge.net