Change Button Label

[Amit Jain <amitjain webdunia com>]

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.

Thanks in Advance
Amit Jain