Sending RoundCube using the application/xhtml+xml mimetype

[octavian_3009]

Hello,
I would like to use content negotiation to send text/html to IE style browsers and application/xhtml+xml to Mozilla style browsers. Thanks to This article, I've been able to fix the validation errors (in roundcube/program/include/rcube_shared.inc) and change the doctypes. The source indicates (because I tell the PHP to send different code with different mimetypes) that the correct mimetype has been sent. However, when I actually check to see which mimetype is being sent to the browser, it always comes up as text/html.
Is there some code preventing me from sending application/xhtml+xml? If so, which file is it in and how can I fix it?

[octavian_3009]

There must be a way to do this. I'm only trying to send the web pages as real XHTML (mimetype: application/xhtml+xml) to browsers that can handle it. I'm so close. Is there maybe a developer who knows which section of code is preventing this?
Any help would be appreciated.

[Julius Caesar]

There must be a way to do this. I'm only trying to send the web pages as real XHTML (mimetype: application/xhtml+xml) to browsers that can handle it. I'm so close. Is there maybe a developer who knows which section of code is preventing this?
Any help would be appreciated.

Developers are hardly here. Please use the mailing lists if you want to contact a developer: Getting help for RoundCube Webmail

[octavian_3009]

Thank you. I will do that.