browser search option ( ctrl + f ) does not work

[palak6041]

When multiselect dropdown is open and we try to search for text on page using browser ctrl + f then broswer search dialog does not get open.

Steps to reproduce the issue

1. Navigate to http://davidstutz.de/bootstrap-multiselect/#further-examples
2. Expand any multiselect dropdown on page
3. when dropdown is expanded then press ctrl + f
4. observe that browser search dialog does not get open

[bjlbernal]

I've observed the same issue.