Why can I select tabs in xterm?
This issue was noted early on, here in 1997. Xterm is copying from the screen, which stores only printable characters. That includes spaces and line-drawing characters. But tabs are special; they are used for more than one purpose. If the screen is cleared in some part, that stores nulls. Cursor addressing does not fill in nulls as it jumps around, though xterm does supply blanks for the most useful cases, especially when getting data for a selection. Full-screen programs such as text-editors tend to write in random fashion, and generally do not print nulls to the screen. Curses on the other hand, may supply tabs where you thought there were none. Also, the terminal driver can expand tabs (and often is set to do this by default). So the whole thing is unreliable: unless you make special arrangements for each of the programs running inside xterm, you would often get a tab when you expect, and vice versa. For the special case where your expectations would match the available data, it is
