Hides the active editor, saving the changes made.
Before the active editor's new value is posted to a data source, it is validated. If a new value is valid, it is posted to a data source and the editor can be closed. Otherwise, if a new value is invalid, the active editor cannot be closed, and cell focus cannot be moved to another cell until its value is corrected.
After the editor has been hidden, the GridViewBase.HiddenEditor event is raised.