When you visit http://slovnik.cz/ a text box is focused where you can type a word
to lookup.  After submitting a query, that box will be focused again, with the text
inside selected, but conkeror is not in Input-mode.  Hitting tab moves focus to the
"přeložit" button, then hitting S-tab will go back to the input box, and conkeror
will then be correctly in Input-mode.  Alternatively, switching out of and back to
conkeror in the window manager causes conkeror to correctly enter Input-mode for
that text field.