class mod_mymodule_compose_form extends moodleform {
....
...

$mform->addElement('file', 'attachment', "File Attachment");
$mform->addElement('submit','attachfile', "Attach File");
...
--------------------------------

The code above works file. But if l change this to group the items so that they will be on the same line as below, l get error when file is submitted:

–
class mod_mymodule_compose_form extends moodleform {
....
...

$marray=array();
$marray[] = &$mform->createElement('file', 'fileattachment', get_string('attachment', "internalmail"));
$marray[] = &$mform->createElement('submit', 'attachfile', "Attach File");
$mform->addGroup($marray, 'attachment', "File Attachment", '', false);
...
-------
The second code does not work. When you click on the "Attach File" submit button, l get an error 'Incorrect upload attempt'. I checked it is it coming from

lib/formslib.php
function _validate_files(&$files) {

If you see my comment above, $mform->getElementType($elname) call in the above function is using an array defined in the forms Object called _elementIndex and this array does not have the index the items that have been added using the addGroup method. Hence it is failing.

http://tracker.moodle.org/browse/MDL-11537#action_35666

This array has the location of the items in the array.

The getElementType function in QuickForm.php depends on this.

But when you had items to a group, the items are not part of this index hence getElementType fails.

It would be nice if getElementType can recurse or somehow find item types in a Groups. Or just add the items in the Groups to this index array.

Let me know when this is fixed and hope it is fixed before 1.9 is released. Thanks for looking at it in the first place.