ActionChange is called automatically when the action object specified by the Action property, or any of its properties, changes. ActionChange updates the control properties that correspond to properties of the associated action. These properties include the Down, ImageIndex, Caption, Enabled, Hint, and Visible properties and the OnClick event handler. 

The Sender parameter is the action object that changed. The CheckDefaults parameter indicates whether the control's properties should all be updated or only those that have not been explicitly changed from their default values. When CheckDefaults is true, only those properties and event handlers that have not been changed from the default values are updated. 

Action 

Down 

ImageIndex 

Caption 

Enabled 

Hint 

Visible 

OnClick