We keep PROOF for those who still need it for legacy use cases. PROOF is not developed anymore and receiving only limited support. ROOT has since a few years moved to RDataFrame and related products as multi-core/multi-processing engines.
RooMultiCatIter is unnecessary, since all multi category classes know how to generate their own states. Use begin() / end() and range-based for loops on instances of these classes.
This function is unneccessary if the template parameter is RooAbsRealLValue (+ derived types) or RooAbsCategoryLValue (+derived types), as arg() will always return the correct type.
Use of TGeoTrack is deprecated. For the event display please switch to TEve (using TEveTracks or TEvePointSet to display tracks specifically) or to REve.
We keep THtml for those who still need it for legacy use cases. ROOT has since several years moved to doxygen as documentation generator. THtml is not developed nor supported anymore; please migrate to doxygen instead.