Custom JavaScript Component breaks tooltips

I have created custom javascript component similar to https://vaadin.com/book/vaadin7/-/page/gwt.javascript.html .
When its added to the UI tooltips are getting broke, they get style less…

it happens when js files getting attached.

browser console error:
Wed Aug 06 16:50:50 GMT+530 2014 com.vaadin.client.VConsole SEVERE: Could not determine ApplicationConnection for Overlay. Overlay will be attached directly to the root panel

please advice…