Sets the label to show on the button.
Underlines in the button text can be used to indicate a mnemonic.
If set to NULL, the button won't be shown.
See propertyToast:action-name.
a button label
Sets the label to show on the button.
Underlines in the button text can be used to indicate a mnemonic.
If set to NULL, the button won't be shown.
See propertyToast:action-name.