The TreeTableView control is a new control targeted at JavaFX 8.0. The Jira issue for this feature request is at RT-17288, but this wiki page should cover the main points in summary.
TreeTableView API Discussion
Discussion of the currently-in-development TreeTableView API, including open questions that need to be discussed further.
TreeTableView API Examples
A number of worked examples demonstrating how to use the TreeTableView API in its current form.
TreeTableView Implementation Details
A brief overview of the implementation details behind the TreeTableView control.
Overview
Content Tools
ThemeBuilder