I have run into an issue which _may_ indicate a bug in the cygwin X11 
server.  The issue is documented here:

    https://bugs.launchpad.net/inkscape/+bug/1365153

In brief, for certain test files viewed in Inkscape (current trunk at 
least) over a putty ssh tunnel from an Ubuntu 12.04lts system to the 
cygwin 1.14.1.0 X11 server there are glitches in the image when it is 
zoomed in and out.  This does not occur if the same program is run 
locally on the console of the test machine.  It also does not happen if 
I run a native Windows version (not cygwin, not X11) of Inkscape on the 
same PC which hosts that X11 server on the same test files.  The glitch 
does not occur with a huge number of other test files I have looked at 
over the years.  It seems there is something specific to the clipping 
code in Inkscape and this particular X11 transport path/server 
combination.  Moreover, it looks like the problem is only manifested (or 
only manifested frequently) when the clipping path consists of two (or 
more?) disjoint sections.

When the glitches occur nothing is added to XWin.0.log.

Also this X11 server is not running in the full cygwin environment, but 
rather in one edited down to just the minimum needed to run the X11 
server.  I distribute this version here:

    http://sourceforge.net/projects/minimalcygwinx/

I don't think this is a factor though, since all of the action is going 
on inside the X11 server process(es).

Thanks,

David Mathog
mathog@caltech.edu
Manager, Sequence Analysis Facility, Biology Division, Caltech