- rewrite the rendering part, use tables instead of absolutely positioned divs
  -> this will enable custom css per table, and per row
- allow event listeners (for keys, mouse, etc)
- add sorting and filtering options.
- make the action buttons more generic, customizable style and functionality
- make rows selectable via a checkbox on the right?
- improve drag and drop. Disable drag and drop when fields are not draggable
- treegrid should not need a fixed container, must be able to just have an
  container that expands instead of getting a vertical scrollbar.