Code from this link may help.
Ctrl-M is an alternative Carriage Return character (CR) - 0x0D.
includes/ui/ui_controls.php has a few shortcut keys defined outside of the functions at lines 443 - 457:
/* Table editor interfaces. Key is editor type
0 => url of editor page
1 => hotkey code
2 => context help
*/
$popup_editors = array(
'customer' => array('/sales/manage/customers.php?debtor_no=',
113, _("Customers"), 900, 500),
'branch' => array('/sales/manage/customer_branches.php?SelectedBranch=',
114, _("Branches"), 900, 700),
'supplier' => array('/purchasing/manage/suppliers.php?supplier_id=',
113, _("Suppliers"), 900, 700),
'item' => array('/inventory/manage/items.php?stock_id=',
115, _("Items"), 800, 600)
);
The "F#" function keys are coded in the succeeding function:
/*
Bind editors for various selectors.
$type - type of editor
$input - name of related input field
$caller - optional function key code (available values F1-F12: 112-123,
true: default)
*/
function set_editor($type, $input, $caller=true)
{
global $path_to_root, $Editors, $popup_editors, $Pagehelp;
$key = $caller===true ? $popup_editors[$type][1] : $caller;
$Editors[$key] = array( $path_to_root . $popup_editors[$type][0], $input,
$popup_editors[$type][3], $popup_editors[$type][4]);
$help = 'F' . ($key - 111) . ' - ';
$help .= $popup_editors[$type][2];
$Pagehelp[] = $help;
}
