Switches to the previous window or switches to the previous sheet in a workbook
static int ActivatePrev( LPCTSTR workbook_text = 0 );
Workbook_text is the name of the workbook for which you want to activate a window. If it is omitted, then the previous workbook will be activated.
Zero if the function has been called successfully; non-zero if the function could not be called. See Error codes for a list of return values.
See the Microsoft Excel on-line Help for full details about this function.