Path: utzoo!utgpu!news-server.csri.toronto.edu!clyde.concordia.ca!uunet!auspex!guy
From: guy@auspex.auspex.com (Guy Harris)
Newsgroups: comp.windows.x
Subject: Re:  X11R4 xterm twists: PageUp/PageDown, Sun4 Numeric/Keypad, etc.
Message-ID: <3826@auspex.auspex.com>
Date: 5 Aug 90 02:22:41 GMT
References: <9007221152.AA00736@shamash.McRCIM.McGill.EDU>
Organization: Auspex Systems, Santa Clara
Lines: 43

>Now, if this is cut, you want to get the former.  But now suppose a
>cursor-address is done and an x is written over the middle space.  The
>display now shows
>
>	f o o SPACE SPACE x SPACE SPACE b a r
>
>If you now cut this, do you expect to get any TABs?

I might.

> If so, where?

In place of the second two SPACEs.

> And above all, why?

Solely in order to get me a TAB in the case where there was only a TAB
sent to the "terminal".

Not giving any TABs would probably also be acceptable; the main reason
I'd want tabs would be if I were cutting text that *hadn't* been
overwritten, although I might want to cut'n'paste from an editor screen
(but in that case I should be running an editor that runs directly under
X, so I'm cutting from the *editor's* buffer rather than the terminal
emulator's buffer; after all, many editor won't literally throw tabs
onto the screen if the line contains tabs, as it may be more efficient
for them to do something else - we would *definitely* be talking DWIM in
that case). 

However:

>Completely correct handling of cuts is dangerously close to "do what I
>mean"; it's nearly impossible to state precisely what cutting should do
>in unclear cases without resulting in an algorithm that badly
>mishandles some clear cases.

is probably applicable here.  I could certainly live with getting SPACEs
(and have done so for several years, with e.g. "shelltool").  When
passing stuff through a program's output code (especially an editor's
screen-display code), a tty driver, and a terminal emulator, there are
plenty of places where information can get irretrievably lost; given
that, it may not be possible to reconstruct that information in a
fashion acceptable to everybody.