This compatibility problem is specific to Internet Explorer 9 and not Roundcube itself. Currently no solution or fix date has been provided by Microsoft.

We would advise to open Roundcube (https://webmail.eu.com/) from another browser, such as Chrome, Firefox or Safari:

http://www.mozilla.org/en-US/firefox/new/
http://www.google.com/chrome/
http://support.apple.com/downloads#internet

Alternatively you can change the compatibility view in Internet Explorer settings, by following these steps: open IE9

• Click on Alt key on the keyboard
• Click on Tools in menu bar
• Select Compatibility View Settings
• Select the box 'Display all websites in Compatibility View'
• Send a test message