https://github.com/DaveDavenport/gpx-viewer/commit/9cb7021c05c118456ec21790d4a9b2454509c3b4

--- data/gpx-viewer-file-chooser.ui.orig	Sun Sep 20 11:15:03 2015
+++ data/gpx-viewer-file-chooser.ui	Sun Sep 20 11:15:08 2015
@@ -7,7 +7,6 @@
     <property name="title" translatable="yes">Choose gpx file(s)</property>
     <property name="icon_name">gpx-viewer</property>
     <property name="type_hint">normal</property>
-    <property name="has_separator">False</property>
     <property name="select_multiple">True</property>
     <property name="filter">gpx_viewer_file_chooser_filter</property>
     <property name="local_only">False</property>