Re: Clearing the buffer after quitting LESS, MAN, VIM etc.

[Christopher Faylor <cgf-use-the-mailinglist-please at cygwin dot com>]

On Mon, Feb 24, 2014 at 12:48:01PM -0500, Christopher Faylor wrote:
>On Mon, Feb 24, 2014 at 05:35:21PM +0000, Dawid Ferenczy wrote:
>>Christopher Faylor <cgf-use-the-mailinglist-please <at> cygwin.com> writes:
>>
>>> Getting that kind of functionality in the Windows console is tricky but
>>> I think it should be there in the latest snapshot.  I also fixed some
>>> problems with some of the escape sequences that scroll the screen.
>>> 
>>> There is still one more difference between Cygwin and, e.g., xterm
>>> though.  The scroll buffer is still there when you enter a full screen
>>> session like vim or less.  So you can scroll up to it and really cause
>>> confusion.  It's possible to fix that behavior but it would be really
>>> tricky.  I'm not sure I want to complicate the console handling code
>>> for this one corner case.
>>> 
>>> The new behavior is in the latest snapshot.
>>> 
>>> http://cygwin.com/snapshots/
>>
>>Thank you very much for your interest. But I have to say, it's now worse 
>>than it was before. I'm using the latest snapshot (2014-02-24).
>
>This wasn't my snapshot, it was Corinna's.  I am still working on the
>problem.

That said, however.  I have checked out the snapshot.

>>My findings:
>>
>>1. Clear screen (CTRL + L) now works better, it simply scrolls to the end 
>>of the scrollback buffer and appends to it. But the screen isn't cleared, 
>>what should be the main purpose of the "clear screen" :) After clearing of 
>>screen, current prompt is on the most bottom line of screen with scrollback 
>>buffer above. I think that it's should be on the first line of screen and 
>>the screen bellow should be empty. So add of scroll screen_height lines 
>>down should be enough to resolve this.

I am aware of how clear screen is supposed to work.  I obviously don't
see this behavior.  I tried this with a cmd window without a scrollback
buffer and with a scrollback buffer at the beginning, middle, and end.

You're going to need to provide details about your console layout.  How
many lines in your buffer?  Where are you when you see this behavior?  In
the middle of the buffer?  Absolute end of the buffer?  Near the end of
the buffer?

I assume you're just using a cmd.exe.  You've probably mentioned if you
are using the 64-bit or 32-bit version but please clarify that again.

>2. Scrollback buffer seems to be fine until I use LESS/VIM etc. 
>(alternative screen). Than it's messed. Alternative screen shouldn't 
>influence the scrollback buffer, I think.

I don't see this.  If you are trying to scroll the screen while in vim
then see my previous observations about this, i.e., "don't do that".

>3. It's incompatible with screen (screen manager). Status line of screen is 
>overwritten with screen content and when screen content reaches the most 
>bottom line of screen, it doesn't scroll, so any additional content is 
>hidden.

I don't see any problems with screen so you're going to have to provide
details about your setup.  Again, however, if you are trying to use the
scrollback buffer while in screen or any other full-screen utility it
isn't going to work well and it has never worked well.

cgf

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