Assembly: System.Web (in System.Web.dll)
The method is a critical method on an AppearanceEditorPart control. It implements the EditorPart.SyncChanges method from the base class, retrieves the current values from the associated WebPart control, and updates the controls in the AppearanceEditorPart control with those values so a user can edit them.
The method is called whenever the values in the associated WebPart control might have changed. For an AppearanceEditorPart control, the EditorZoneBase zone that contains the control calls the method, so that the values in the AppearanceEditorPart control are always synchronized with the values in the associated WebPart control. Another case where the method is called is when a WebPart control is entering edit mode.Notes to Inheritors
The Web Parts control set calls the method within the inherited OnPreRender method, so that if any changes occurred after the user last viewed the control prior to editing (for example, a shared administrative user made changes to the control that would affect all users), those changes would be evident during the editing process.
If you create a custom control, you can follow the same approach, and call the method from the inherited OnPreRender method to ensure that any intervening changes are synchronized, but it is not necessary to do this.