Offline contribution form: From Email Address field is hidden even though Send Receipt is checked (on form reloads)

The javascript code in Contribution.tpl which is supposed to "show" from_email_address field when is_email_receipt is checked does not work if form is reloaded due to form validation errors. In this case, the Send Receipt box is checked but the From Email dropdown is hidden.

(There is a "messy" mix of jQuery and old-style jscript functions in the tpl file which should be cleaned up.)