Called when the default implementation dialog is closed.

When leaving the page a Javascript dialog is displayed asking for user confirmation. Returning True allows you to implement a custom dialog or programatically handle. To cancel the unload return True and set allowUnload to False.

Called to run a JavaScript dialog.

Called to cancel any pending dialogs and reset any saved dialog state. Will be called due to events like page navigation irregardless of whether any dialogs are currently pending.