+or the underlying w3m... Perhaps I'll report this issue to them. --Ivan Z.
+
+[[!tag done]]
+There is no problem at all!
+I'm sorry for this hassle!
+In emacs-w3m, there is the <code>w3m-submit-form</code> command
+(<kbd>C-c C-c</kbd>) to submit the form at point; it works.--Ivan Z.