After running a report and making the browser window width small enough, two horizontal scroll bars appear - one for the browser and one for the report body. This occurs because the report header (containing the pagination and save buttons) has a larger min-width than the report body. If the header and the body had the same min-width, they would stop resizing at the same point and no horizontal scroll bar would be created in the report body.
Steps to reproduce:
1. Run a Jasper report
2. Make the browser window width smaller until two horizontal scroll bars appear (see attached screen shot)
Note: This bug was found in version 5.2 but most likely exists in every release that has a report header.