Since Charles "broke" the validation with his sub-folder highlighting stuff, I also noticed that in general, Roundcube won't validate because of the "search" type of input.

XHTML 1.0 Transitional DTD: link http://www.w3.org/TR/xhtml1/dtds.html#dtdentry_xhtml1-strict.dtd_InputType

<!ENTITY % InputType "(text | password | checkbox | radio | submit | reset | file | hidden | image | button)" >

<!-- the name attribute is required for all but submit & reset -->

<!ELEMENT input EMPTY> <!-- form control -->

<!ATTLIST input <http://www.w3.org/TR/xhtml1/dtds.html#dtdentry_xhtml1-strict.dtd_input>

%attrs; http://www.w3.org/TR/xhtml1/dtds.html#dtdentry_xhtml1-strict.dtd_attrs %focus; http://www.w3.org/TR/xhtml1/dtds.html#dtdentry_xhtml1-strict.dtd_focus type %InputType; http://www.w3.org/TR/xhtml1/dtds.html#dtdentry_xhtml1-strict.dtd_InputType "text" name CDATA #IMPLIED value CDATA #IMPLIED checked (checked) #IMPLIED disabled (disabled) #IMPLIED readonly (readonly) #IMPLIED size CDATA #IMPLIED maxlength %Number; http://www.w3.org/TR/xhtml1/dtds.html#dtdentry_xhtml1-strict.dtd_Number #IMPLIED src %URI; http://www.w3.org/TR/xhtml1/dtds.html#dtdentry_xhtml1-strict.dtd_URI #IMPLIED alt CDATA #IMPLIED usemap %URI; http://www.w3.org/TR/xhtml1/dtds.html#dtdentry_xhtml1-strict.dtd_URI #IMPLIED onselect %Script; http://www.w3.org/TR/xhtml1/dtds.html#dtdentry_xhtml1-strict.dtd_Script #IMPLIED onchange %Script; http://www.w3.org/TR/xhtml1/dtds.html#dtdentry_xhtml1-strict.dtd_Script #IMPLIED accept %ContentTypes; http://www.w3.org/TR/xhtml1/dtds.html#dtdentry_xhtml1-strict.dtd_ContentTypes #IMPLIED

...

So that won't validate since in XHTML 1.0, "search" isn't a valid input type :(

Even the XHTML 1.1 spec doesn't have "search" as an input type:

<!ENTITY % input.attlist "INCLUDE" >

<![%input.attlist;[

<!ENTITY % InputType.class "( text | password | checkbox | radio | submit | reset | file | hidden | image | button )" >

<!-- attribute 'name' required for all but submit & reset -->

<!ATTLIST %input.qname; %Common.attrib; type %InputType.class; 'text' name CDATA #IMPLIED value CDATA #IMPLIED checked ( checked ) #IMPLIED disabled ( disabled ) #IMPLIED readonly ( readonly ) #IMPLIED size %Number.datatype; #IMPLIED maxlength %Number.datatype; #IMPLIED src %URI.datatype; #IMPLIED alt %Text.datatype; #IMPLIED tabindex %Number.datatype; #IMPLIED accesskey %Character.datatype; #IMPLIED accept %ContentTypes.datatype; #IMPLIED >

I know Safari is supporting this, and with it the "results" attribute, but it won't validate.

Not sure if you're working off of a different spec or not. Just thought I'd point it out ;)

~Brett