GUIBaseContext :: doBeforeSaveClose - Pre-event handler for SaveClose action

The handler handles the DEV_SaveClose data event in a SaveClose action. When the event is fired, the property handle is still opened and data can be accessed. The event must be handled, when data for the control needs to be stored before closing the control and its data source (property handle). The event is typically used to close (commit) transactions in a transaction-save dialog.

The event handler may prevent the dialogue or application from being closed by returning true, in which case data is not saved and the control remains opened.

The handler should return one of the following values:

• -1 (not handled) - the event handler will be removed from the handler list and is not called anymore.
• 1 (refuse) - Requested action is not executed.
• 0 (ok) - Action is permitted to be executed.