if user is xfce4 user [startxfce4 or xfce4-session in running procs] then use exo-open (needs libexo) to open urls using the xfce defined default apps

data/glade/preferences_window.glade

@@ -3001,6 +3001,7 @@ Disabled</property>
 			      <property name="items" translatable="yes">Autodetect on every Gajim startup
 Always use GNOME default applications
 Always use KDE default applications
+Always use XFCE4 default applications
 Custom</property>
 			      <property name="add_tearoffs">False</property>
 			      <property name="focus_on_click">True</property>

src/config.py

@@ -929,7 +929,7 @@ class PreferencesWindow:
 
 	def on_applications_combobox_changed(self, widget):
 		gajim.config.set('autodetect_browser_mailer', False)
-		if widget.get_active() == 3:
+		if widget.get_active() == 4:
 			self.xml.get_widget('custom_apps_frame').show()
 			gajim.config.set('openwith', 'custom')
 		else:
@@ -939,6 +939,8 @@ class PreferencesWindow:
 				gajim.config.set('openwith', 'gnome-open')
 			elif widget.get_active() == 2:
 				gajim.config.set('openwith', 'kfmclient exec')
+			elif widget.get_active() == 3:
+				gajim.config.set('openwith', 'exo-open')
 			self.xml.get_widget('custom_apps_frame').hide()
 		gajim.interface.save_config()
 

src/gtkgui_helpers.py

@@ -188,6 +188,8 @@ def autodetect_browser_mailer():
 		gajim.config.set('openwith', 'gnome-open')
 	elif user_runs_kde():
 		gajim.config.set('openwith', 'kfmclient exec')
+	elif user_runs_xfce():
+		gajim.config.set('openwith', 'exo-open')
 	else:
 		gajim.config.set('openwith', 'custom')
 
@@ -197,6 +199,12 @@ def user_runs_gnome():
 def user_runs_kde():
 	return 'startkde' in get_running_processes()
 
+der user_runs_xfce():
+	procs = get_running_processes()
+	if 'startxfce4' in procs or 'xfce4-session' in procs:
+		return True
+	return False
+
 def get_running_processes():
 	'''returns running processes or None (if not /proc exists)'''
 	if os.path.isdir('/proc'):