Thanks! I’d appreciate it if this thread could stay on-topic though, but here you go:
Mostly historical reasons, but also technical and practical ones. Among other things the widget is likely to break until it has been properly configured (e.g. assigned an item).
You have an “experimental” dashboard option in the Advanced tab to change the number of columns in the grid from the default (12).
It’s part of the distribution and the latest version at the time of build is included. You can also update manually.
Edit: there is now a comprehensive documentation on HABPanel in the official openHAB docs: