This function shows this to the user.
The callback will be called when the alert is dismissed. It should call [method@AlertDialog.choose_finish] to obtain the
result.
If the window is an [class@Window] or [class@ApplicationWindow], the dialog will be shown within it. Otherwise, it will be a separate window.
| this |
an alert dialog |
| parent |
the parent widget |
| cancellable |
a `GCancellable` to cancel the operation |
| callback |
a callback to call when the operation is complete |
| user_data |
data to pass to |