Fwd: Limited clipboard buffer between X11 apps and Microsoft Windows

Jon Turney jon.turney@dronecode.org.uk
Fri Feb 19 16:25:00 GMT 2016

On 19/11/2015 12:30, Jon Turney wrote:
> On 17/11/2015 18:57, Kevin Connor Arpe wrote:
>> My issue: Copying text between X11 apps and Microsoft Windows has
>> limited clipboard buffer.  My office co-worker and I were able to
>> replicate the same issue on our machines.
>> To replicate:
>> 1) Run Cygwin X Server locally.
>> 2) Run gedit remotely (using company Linux hosts) and redirect display
>> to our local Cygwin X Server.
>> 3) Copy some text in gedit, paste in Windows app, e.g. Notepad.
>> We are able to find a limit (approximately 1000+ lines of text).  To
>> be very clear:  We can copy small amounts to text, but not large
>> amounts of text.
>> My co-worker found this historical Cygwin mailing list item.  It looks
>> very similar:
>> http://cygwin.1069669.n5.nabble.com/emacs-x11-new-clipboard-size-limitation-td104696.html
>> When the copy/paste fails, I see the following in
>> /var/log/xwin/XWin.0.log:
>> [298268.591] winClipboardFlushXEvents - SelectionNotify -
>> X*TextPropertyToTextList returned: XConverterNotFound
> Thanks for reporting this issue.
> Unfortunately, I don't think this is a recurrence of the regression in
> that old report.
> Briefly, there is a different protocol [1] for transferring clipboard
> contents too large to fit in a single X protocol message (approximately
> 262144 bytes), which is not currently implemented by the X11/Windows
> clipboard synchronization code.
> Your estimate of 1000 lines seems a little low, but in my testing this
> is the limit I hit.
> [1]
> http://www.x.org/releases/X11R7.7/doc/xorg-docs/icccm/icccm.html#INCR_Properties

This should be fixed in X server 1.18.1-1 I uploaded today.

Note there is still a limit of approx. 16MB when copying in the opposite 
direction (from a Windows app to an X11 app), but that is harder to fix...

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