TI/TE disabling support

One of the things that has kept me using xterm is that I can disable the ti/te "alternate window" mode. Typically it is vim/nvim and less that use it, but I *like* the ability to have my editing session or man page or whatnot stay on the screen rather than vanishing. Most alternative terminal emulators I've tried over the decades have not supported the ability to disable it, and I've tired of the various hacks.