Description of problem:
I was viewing calendar invites (EWS), and switched focus from one in my inbox to another in my inbox.  The crash occurred then.  However, this does appear intermittent, since I was just doing this same operation a few minutes prior to the crash.

Version-Release number of selected component:
evolution-3.8.3-2.fc19

Additional info:
reporter:       libreport-2.1.5
backtrace_rating: 4
cmdline:        evolution
crash_function: proxy_pixbuf_destroy
executable:     /usr/bin/evolution
kernel:         3.9.9-302.fc19.x86_64
runlevel:       N 5
uid:            1000

Truncated backtrace:
Thread no. 1 (10 frames)
 #4 proxy_pixbuf_destroy at gtkicontheme.c:3515
 #5 gdk_pixbuf_finalize at gdk-pixbuf.c:259
 #7 cached_icon_free at gtkiconfactory.c:2574
 #8 clear_cache at gtkiconfactory.c:2701
 #9 g_hash_table_foreach at ghash.c:1526
 #10 style_dnotify at gtkiconfactory.c:2797
 #11 g_datalist_clear at gdataset.c:277
 #13 cached_icon_free at gtkiconfactory.c:2575
 #14 add_to_cache at gtkiconfactory.c:2668
 #15 gtk_icon_set_render_icon_pixbuf at gtkiconfactory.c:1754