I install the OSX winswitch package and run xpra from it. I run the script that sets up the dynamic libs, etc. here:

/Applications/Window-Switch.app/Contents/Helpers/xpra

This script has the odd behavior of not working unless you run it from a parent dir of the script. Otherwise you get

$ /Applications/Window-Switch.app/Contents/Helpers/xpra
/Applications/Window-Switch.app/Contents/Helpers/xpra: line 77: /Users/troy//Applications/Window-Switch.app/Contents/Resources/bin/xpra: No such file or directory
/Applications/Window-Switch.app/Contents/Helpers/xpra: line 77: exec: /Users/troy//Applications/Window-Switch.app/Contents/Resources/bin/xpra: cannot execute: No such file or directory

I think the issue is at the top of the file

if [[ "$0" == `pwd`* ]] || [[ "$0" == "//"* ]]; then
    full_path="$0"
else
    full_path="`pwd`/$0"
fi

On Debian presence of package 'openstreetmap-map-icons-scalable' lead to the following crash:

[EE] 2012/10/08 02:26:45 icon_util.load_pixmap_file(/usr/share/icons/openstreetmap/scalable/recreation/theater.svg,48)
[ee] 2012/10/08 02:26:45 Traceback (most recent call last):
[ee] 2012/10/08 02:26:45   File "/usr/lib/python2.7/dist-packages/winswitch/util/icon_util.py", line 71, in load_pixmap_file
[ee] 2012/10/08 02:26:45     return cairo_load_svg(filename, size_limit)
[ee] 2012/10/08 02:26:45   File "/usr/lib/python2.7/dist-packages/winswitch/util/icon_util.py", line 107, in cairo_load_svg
[ee] 2012/10/08 02:26:45     scale = min(size_limit/float(svgwidth), size_limit/float(svgheight))
[ee] 2012/10/08 02:26:45 ZeroDivisionError: float division by zero
Segmentation fault

Here is the contents of /usr/share/icons/openstreetmap/scalable/recreation/theater.svg

<?xml version="1.0" encoding="utf-8"?>
<svg xmlns="http://www.w3.org/2000/svg">
    <defs>
        <symbol id="symbol-theatre" viewBox="220 207 440 550">
            <g stroke="none" fill-opacity="1" fill-rule="nonzero">
                <path d="M192.4,22c0,0,50,26,112,20s94-39,98-42s17,32,17,32l4,33l-3,29l5,24l7,39l-5,32l-6,32l-19,55l-25,49l-59,21l-30-14l-22-22l-29-47l4-40l-20-28l-18-24l1-34l2-54l-8-35L192.4,22z"/>
                <path fill="none" stroke="#FFFFFF" stroke-width="10" d="M210.4,44.5c0,0,43.8,22.8,98,17.5s82.3-34.1,85.8-36.8s14.9,28,14.9,28l3.5,28.9l-2.6,25.4l4.4,21l6.1,34.1l-4.4,28l-5.3,28l-16.6,48.1l-21.9,42.9L320.6,328l-26.3-12
                <path fill="#FFFFFF" d="M293.4,152c0,8.3-11.4,15-25.5,15s-25.5-6.7-25.5-15s11.4-15,25.5-15S293.4,143.7,293.4,152z"/>
                <path fill="#FFFFFF" d="M406.4,140.5c0,8.6-13.2,15.5-29.5,15.5s-29.5-6.9-29.5-15.5s13.2-15.5,29.5-15.5S406.4,131.9,406.4,140.5z"/>
                <path fill="none" stroke="#FFFFFF" stroke-width="10" d="M248.4,124l14-43l15,27"/>
                <path fill="none" stroke="#FFFFFF" stroke-width="10" d="M336.4,110l7-32l35,23"/>
                <path fill="none" stroke="#FFFFFF" stroke-width="10" d="M317.4,146l-7,72l22-1L317.4,146z"/>
                <path fill="none" stroke="#FFFFFF" stroke-width="10" d="M305.4,297c0,0,2-55,27-57s37,16,41,30"/>
                <path fill="#FFFFFF" stroke="#000000" stroke-width="10" d="M207.4,90c0,0-19,18-61,17s-42,5-83-33s-31-38-31-38l-9,105l-5,22l-13,15l26,128l37,82c0,0,3,9,38,9s30-10,40-20s15-35,34-49s41-47,41-47l17-21l3-34l-23-29l-12-32L
                <path fill="none" stroke="#000000" stroke-width="10" d="M51.4,150c0,0-2-15,25-15s31,17,31,17"/>
                <path fill="none" stroke="#000000" stroke-width="10" d="M153.4,168c0,0,6-11,12-14s22,5,22,5"/>
                <path d="M51.4,193l23-19c0,0,12-2,25,2s7,14,7,14L51.4,193z"/>
                <path d="M164.4,199c0,0,14-13,27-10s16,19,16,19s-7,6-26,1S164.4,199,164.4,199z"/>
                <path d="M125.4,188l-25,83h29L125.4,188z"/>
                <path d="M61.4,258c0,0,0-4,14,16s10,36,44,34s38-45,55-42s13,8,7,20s-23,23-32,35s5,40-39,38s-43-44-49-48S61.4,258,61.4,258z"/>
            </g>
        </symbol>
    </defs>
</svg>

 [EE] 2012/09/08 23:34:28 icon_util.load_pixmap_file(/usr/share/icons/mono/scalable/apps/abiword.svgz,48)
  [ee] 2012/09/08 23:34:28 Traceback (most recent call last):
  [ee] 2012/09/08 23:34:28   File "/usr/lib/python2.7/dist-packages/winswitch/util/icon_util.py", line 71, in load_pixmap_file
  [ee] 2012/09/08 23:34:28     data = gtk_load_scaled_pixmap(filename, size_limit)
  [ee] 2012/09/08 23:34:28   File "/usr/lib/python2.7/dist-packages/winswitch/util/icon_util.py", line 38, in gtk_load_scaled_pixmap
  [ee] 2012/09/08 23:34:28     pixbuf = gtk.gdk.pixbuf_new_from_file(filename)
  [ee] 2012/09/08 23:34:28 GError: Couldn't recognize the image file format for file '/usr/share/icons/mono/scalable/apps/abiword.svgz'
  [EE] 2012/09/08 23:34:30 icon_util.load_pixmap_file(/usr/share/icons/mono/scalable/apps/synaptic.svgz,48)
  [ee] 2012/09/08 23:34:30 Traceback (most recent call last):
  [ee] 2012/09/08 23:34:30   File "/usr/lib/python2.7/dist-packages/winswitch/util/icon_util.py", line 71, in load_pixmap_file
  [ee] 2012/09/08 23:34:30     data = gtk_load_scaled_pixmap(filename, size_limit)
  [ee] 2012/09/08 23:34:30   File "/usr/lib/python2.7/dist-packages/winswitch/util/icon_util.py", line 38, in gtk_load_scaled_pixmap
  [ee] 2012/09/08 23:34:30     pixbuf = gtk.gdk.pixbuf_new_from_file(filename)
  [ee] 2012/09/08 23:34:30 GError: Couldn't recognize the image file format for file '/usr/share/icons/mono/scalable/apps/synaptic.svgz'

The problem can be fixed with the attached patch.