When a form is validated, all validation buttons are automatically
locked to prevent them from being sent twice by mistake. When the form
returns a file instead of redirecting to a new HTML page, a mechanism
(\core_form\util::form_download_complete()) must be called to
reactivate the form's validation buttons.
This mechanism is called for CSV files (file lib/csvlib.class.php), but
not when downloading xls files. The mechanism is only called when
downloading grades in Excel format (file
grade/export/xls/grade_export_xls.php).
The patch proposes to call this mechanism globally for all Excel file
downloads (file lib/excellib.class.php), and not just for grade
downloads (file grade/export/xls/grade_export_xls.php).
Julien Boulen
50d583d951