Copy/Paste

[Gordon Messmer]

Bill Gradwohl wrote:
> 
> Sometimes this works, and other times it doesn't. In general, I can't
> figure out where the "clipboard" is that holds the copied text, and what
> causes the inconsistent operation. Is it Gnome, OO, X, me? What is
> causing the seemingly random operation?

This page describes some of the details:
http://www.jwz.org/doc/x-cut-and-paste.html

The first part of the page explains the X mechanisms in general.

Basically, you should know that there's a difference between the "select 
and middle-click" and the "Copy -> Paste" mechanisms.  The difference 
isn't so much in their implementation, but that they grab different 
clipboard contents.  The former uses the "primary" selection, and the 
latter uses the "clipboard" selection.

The other thing you should be aware of is that for memory and network 
efficiency, the clipboard isn't in the X server.  Instead, the clipboard 
is in the application that last copied data.  When an application 
requests a paste operation, it asks the X server which application has 
the clipboard, and then asks that application for the clipboard contents.

> If I copy from the terminal window and then paste it back into the same
> terminal window, or a new terminal window, it works. However, there is
> no Paste option available in OO at times.

That's probably because there is no clipboard selection.  The paste 
operation will only use the clipboard selection.  If you highlight text 
in any application, you create a context for the primary selection, but 
the clipboard selection will only be available after you explicitly ask 
the application to "copy" the highlighted information.

> If I open up an emacs editor,
> I can paste that text into its scratch window. Why won't OO see the same
> clipboard area?

Emacs is particularly confusing with regards to its use of primary 
selection, because it may overlap with emacs' own internal kill-ring 
history.

The second part of the above referenced page describes how Emacs and 
XEmacs use the X copy and paste mechanism, and how those two programs 
differ.

> I've also noticed that if I copy from a particular window (terminal
> window) and then close that window, that the copied text also
> disappears. That seems to say that the copied text is somehow connected
> to the window from where it came and there is no central clipboard.

That's right.