i accept it as it is really - pondering is somewhat pointless as we probably will get no help from the devs - the best we can hope for is to keep trying an mxskin file in maxthon3/skins and hope one works - thats how i remember it on 4 - old skins just started working - no announcement or anything - i dont think skins as you and i understand them are on the roadmap - they just dont seem bothered
if they dont add full skin support then there will be 0.dat files uploaded i guess just as there were ui.dat files for 4 - someone has decided [at the moment certainly] that the skin they supply is fine - a bit like Microsoft and Windows 10 - themes on that at the moment are hard work