Occurs before showing a dialog window.
property OnShowingDialog: TNotifyEvent;
This event occurs if UserInterface=True.
It is called when properties of the action are already assigned from attributes of the selected text of the target editor, but the dialog is not initialized yet.
In this event, you can modify properties of the action, so modified properties will be applied to the dialog.
You can use this event to initialize a dialog with predefined values, instead of taking them from a selected text.