If you appreciate what the Tesseract project does for you, consider donating to it.
The Display Controller is a controller that acts as FE plug-in. It thus coordinates the work of the other components to produce output that is integrated into the TYPO3 page rendering process. The Display Controller defines relationships between the various components.
This extension provides debugging output using the Kint library. This used to be integrated into displaycontroller itself. It was moved out of the extension after improvements in the debugging output. It is not an officially published extension and must be gotten directly from Github:
The Advanced Display Controller provides the same functionality as the "regular" displaycontroller. The difference is that it can accept many Data Providers at once. This is useful in some cases where it is needed to mix data from different data sources inside the same content element. In that case the Advanced Display Controller is able to deliver a “multi-Data Structure” to the Data Consumer.
This was an early attempt to improve the debugging output of displaycontroller by adding some kind of floating control panel in the TYPO3 frontend. This never worked out really properly and the project was abandoned in favor of other improvements directly in displaycontroller.