Creates a new Button containing a mnemonic label and a stock icon.
The stock_id could be something like OK or
APPLY.
When the stock_id is null a normal mnemonic button will be created, when label
is null a stock button will be created. This behaviour is added for
message_dialog_new.
| stock_id |
the name of the stock item. |
| label |
the text of the button, with an underscore in front of the mnemonic character. |
|
the newly created Button widget. |