howto create a menu title with line break

[pixotec]

Hi, I created a template with tabs.
When creating a new page, I just can enter the menu link text in a (single line) textfield.
When I try to style it like this: "first line<br>second line" "<br>" is shown instead interpreted as HTML.

Example:
How it looks single line: http://www.helmut-danner.info/wb/
How I want it: http://www.helmut-danner.info/

Any workaround (in show_menu2) possible?