There have been so many threads about the html breaks in Spreadfirefox textareas that I am creating a new one. To prevent a textarea on a form from breaking across the page, change the $form to $group and provide a definition of the group before form_submit. Here is an example from the feedback module. The original lines of code read as follows:
if ( variable_get("feedback_field_body", t('Message')) )
$form .= form_textarea (t("Message"), "form_field_body",
$edit['form_field_body'], 60, 15, NULL, NULL, TRUE);
$form .= form_hidden ("form_field_referer", $_SERVER[HTTP_REFERER]);
$form .= form_submit (t("Send message"), "op", $edit['op'] );
The altered code reads as follows:
if ( variable_get("feedback_field_body", t('Message')) )
$group_1 .= form_textarea (t("Message"), "form_field_body",
$edit['form_field_body'], 60, 15, NULL, NULL, TRUE);
$form .= form_hidden ("form_field_referer", $_SERVER[HTTP_REFERER]);
$form .= form_group(t(''), $group_1);
$form .= form_submit (t("Send message"), "op", $edit['op'] );
A title for the form_group was left blank so as not to alter the form. "Fieldset" in style.css can be altered to blend the form_group box with the rest of the form. If you are having problems with content being pushed down in Spredfirefox, please see this post: http://drupal.org/node/51129#comment-107930