Bug: error message about setting default

Even if Slimjet is set as default browser via "preferred applications", still get this error message when clicking on link to forum within email message:

Unfortunately you must have done a smaller thumbnail imgur upload on that one. The image is such low quality I am unable to read the text on the error message. Could you please upload another screenshot that is better quality? If you use the included screenshot utility, copy the code under 'BBcode for forums', and paste it here, it will show up as picture and will be much better quality. Thanks!