On 02 Jul 2002, stephen(a)xemacs.org wrote:
 I'm going to leave the default on "correct behavior",
and work on
 PROBLEMS and the FAQ.  Proposed FAQ follows, comments requested. 
Yea.
 PROBLEMS will just refer to the FAQ, both Info and a web URL.
 
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 @node Q3.10.6,  , Q3.10.5, Customization
 @unnumberedsubsec Q3.10.6: Why is killing so slow?
 
 This actually is an X Windows question, although you'll notice it with
 keyboard operations as well as while using the GUI.  Basically, there
 are four ways to communicate interprogram via the X server:
 
 @c This should be an @table.
     Primary selection:    a transient selection that gets replaced every
                           time a new selection is made
     Secondary selection:  for "exchanging" with the primary selection
     Cut buffers:          a clipboard internal to the X server (deprecated)
     Clipboard selection:  a selection with a notification protocol that
                           allows a separate app to manage the clipboard
 
 The cut buffers are deprecated because managing them is even more
 inefficient than the clipboard notification protocol.  The primary
 selection works fine for many users and applications, but is not very
 robust under intensive or sophisticated use.
 
 In Motif and MS Windows, a clipboard has become the primary means for
 managing cut and paste.  These means that "modern" applications tend to
 be oriented toward a true clipboard, rather than the primary selection.
 (On Windows, there is nothing equivalent to the primary selection.)
 It's not that XEmacs doesn't support the simple primary selection
 method, it's that more and more other applications don't.
 
 So the slowdown occurs because XEmacs now engages in the clipboard
 notification protocol on @emph{every} kill.  This is especially slow on
 Motif.
 
 With most people running most clients and server on the same host, and
 many of the rest working over very fast communication, you may expect
 that the situation is not going to improve. 
Add more words here along the lines of "people running xemacs remotely
over x11 can see cut/kill operations take >5 seconds, particularly
when running motif"
 
 If you are communicating by cut and paste with applications that use
the
 primary selection, then you can customize `interprogram-cut-function' to
 nil, restoring the XEmacs version 20 behavior.  How can you tell if a
 program will support this?  Motifly-correct programs require the
 clipboard; you lose.  For others, only by trying it.  You usually don't
 need to customize the complementary `interprogram-paste-function' to
 nil; presumably you're willing to wait for a paste from another program
 if delays only happen when you specifically request a paste. 
Both interprogram-cut-function and interprogram-paste-function must
be customized together.  Paste is fast (for me) while cut takes ~5seconds.
You can still communicate with motif correct programs by using the
separate toolbar cut/copy function.
 You can get some relief on Motif by setting
 `x-selection-strict-motif-ownership' to nil, but this means you will
 only intermittently be able to paste XEmacs kills to Motif applications. 
Maybe suggest this before interprogram cut/paste?
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