Could be all sorts of things going wrong. As you've probably worked out the relevant JavaScript is in js/resizable.js.php. I think you're just going to have go through this and find out what's going wrong using a few console.log() calls. However here are some pointers which may help:

  • the JavaScript relies on picking up some information about the main table from data- attributes in the HTML
  • it also needs to know what page it's on: it gets this information from

For fixing the header you could try fixing the position of the header user position: fixed and give it a positive z-index so that the rest of the page slides underneath it.