Leaderboard

Absolutely echo what Shaun says. Nobody banned them. But most who tried to use them have after some more or less short time run from them, with many hairs ripped out of their head, a few nervous tics from to much caffeine consume and swearing to never try them again. The idea is not really bad and if you are willing to suffer through it you can make pretty impressive things with them, but the execution of that idea is anything but ideal and feels in many places like a half thought out idea that was eventually abandoned when it was kind of working but before it was a really easily usable feature.

They aren't banned. They are just very hard to debug when they don't work and have some unintuitive behaviours. I have Toolbar and Tab pages XControls that I use all the time and there is a markup string xcontrol here. If you are a real glutton for punishment you can play with xnodes too