([string label = null
[, bool use_underline = false
Use the constructor to create a new check-box. You may pass a string as
the first parameter to display that as a label next to the toggle
button. Also, passing true as the second parameter
with assign the letter that is preceded by an underscore in the label
as the mnemonic for the check-box.
This class is derived and therefore behaves much like a
GtkToggleButton. Hence, you may use the signal
"toggled" to determine
any change in the state of the check-box.