Xfce Wiki

Sub domains

Site Tools

Translations of this page?:

Xfce Panel Plugins How To

You can get the sample plugin from git.


Starting from version 4.4 the Xfce Panel support two types of plugins: internal and external. The internal plugins are loadable modules, using the GModule interface. External plugins are separate programs that are embedded into the panel using the GtkPlug and GtkSocket mechanism.

In order to handle these plugins the plugin system was entirely rewritten, along with the rest of the panel framework. This file describes the way plugin writers should interact with this system.

The API documentation is installed with the panel and also available from http://www.xfce.org/documentation/api/

.desktop file

New in version 4.4 is the requirement for a so called .desktop file, that is pluginname.desktop, to be installed. It should look like this for an external plugin:

[Xfce Panel]
_Name=Plugin name
_Comment=Plugin description

For the internal plugin you would use:


For instance,


If the module should have no more than 1 instance running at the same time, you add this line:


If the plugin is compatible with GTK+ 3, you need to add this line:



The necessary widgets are provided by libxfce4panel. In your configure.ac you should add a line like this:

XDT_CHECK_PACKAGE ([LIBXFCE4PANEL], [libxfce4panel-1.0], [])

The above assumes that you are using the xfce4-dev-tools package, which you really should, because it will make your life easier. Otherwise, you'd have to adjust it to include the relevant PKG_CONFIG macro.

Header File

There is only one header file that needs to be included, which will take care of including other required headers (gtk and libxfce4util):

#include <libxfce4panel/xfce-panel-plugin.h>

Plugin Registration

To register a plugin with the plugin system there are two macros available that should be used, instead of using the library functions directly; one for internal plugins and one for external plugins.


The 'construct' argument is the name of a function that may be cast to XfcePanelPluginFunc, i.e. it takes a single XfcePanelPlugin pointer as argument. In the function all widgets should be created and callbacks connected to the appropriate plugin signals (see below).

example usage

static void plugin_construct (XfcePanelPlugin *plugin);


/* implement functions */


There are several signals that plugins may be interested in:

orientation changed

user_function (XfcePanelPlugin *plugin, 
               GtkOrientation   orientation,
               gpointer         user_data);

screen position changed

user_function (XfcePanelPlugin    *plugin,
	       XfceScreenPosition *position,
	       gpointer            user_data);

The XfceScreenPosition describes the position of the panel on the screen. There are 12 positions, 3 on each side, plus two floating positions.

typedef enum
    /* top */
    XFCE_SCREEN_POSITION_NW_H,          /* North West Horizontal */
    XFCE_SCREEN_POSITION_N,             /* North                 */
    XFCE_SCREEN_POSITION_NE_H,          /* North East Horizontal */
    /* left */
    XFCE_SCREEN_POSITION_NW_V,          /* North West Vertical   */
    XFCE_SCREEN_POSITION_W,             /* West                  */
    XFCE_SCREEN_POSITION_SW_V,          /* South West Vertical   */
    /* right */
    XFCE_SCREEN_POSITION_NE_V,          /* North East Vertical   */
    XFCE_SCREEN_POSITION_E,             /* East                  */
    XFCE_SCREEN_POSITION_SE_V,          /* South East Vertical   */

    /* bottom */
    XFCE_SCREEN_POSITION_SW_H,          /* South West Horizontal */
    XFCE_SCREEN_POSITION_S,             /* South                 */
    XFCE_SCREEN_POSITION_SE_H,          /* South East Horizontal */

    /* floating */
    XFCE_SCREEN_POSITION_FLOATING_H,    /* Floating Horizontal */
    XFCE_SCREEN_POSITION_FLOATING_V,    /* Floating Vertical */

Several macros are defined to make it easier to work with screen positions:


size changed

This function will return TRUE when you handle the size change

user_function (XfcePanelPlugin *plugin, 
               gint             size,
               gpointer         user_data);

free data

user_function (XfcePanelPlugin *plugin,
	       gpointer         user_data);


user_function (XfcePanelPlugin *plugin,
	       gpointer         user_data);


user_function (XfcePanelPlugin *plugin,
	       gpointer         user_data);

To show the menu item the plugin writer should also call:

xfce_panel_plugin_menu_show_about (XfcePanelPlugin *plugin);


user_function (XfcePanelPlugin *plugin,
	       gpointer         user_data);

To show the menu item the plugin writer should also call:

xfce_panel_plugin_menu_show_configure (XfcePanelPlugin *plugin);


Several functions are available to get more information about the plugin (and the panel it is part of). Only one property can also be changed, the 'expand' behavior. The plugin API also provides convenience functions to store and retrieve a pointer to user data.

/* identification */
const gchar *
xfce_panel_plugin_get_name (XfcePanelPlugin *plugin);

const gchar *
xfce_panel_plugin_get_id (XfcePanelPlugin *plugin);

const gchar *
xfce_panel_plugin_get_display_name (XfcePanelPlugin *plugin);
/* getting properties */
xfce_panel_plugin_get_size (XfcePanelPlugin *plugin);

xfce_panel_plugin_get_screen_position (XfcePanelPlugin *plugin);

xfce_panel_plugin_get_expand (XfcePanelPlugin *plugin);

xfce_panel_plugin_get_orientation (XfcePanelPlugin *plugin);
/* settings properties */
void xfce_panel_plugin_set_expand (XfcePanelPlugin *plugin, 
                                   gboolean         expand);

The plugin has a right-click mouse menu connected to it that allows the user to show the about or settings dialog, to remove the plugin, or to show the panel settings dialog. Plugin writers have to make sure all widgets in the plugin that receive mouse events are connected to the menu by using the xfce_panel_plugin_add_action_widget() function. A plugin can also add additional, custom menu items.

IMPORTANT: If your custom menu item allows changes to the plugin, make sure it is safe when running in Kiosk mode!

xfce_panel_plugin_add_action_widget (XfcePanelPlugin *plugin, 
                                     GtkWidget       *widget);
xfce_panel_plugin_menu_insert_item (XfcePanelPlugin *plugin,
                                    GtkMenuItem     *item);

If your plugin has a configuration dialog you need to make that menu item visible and connect to the “configure-plugin” signal. The same for an about dialog and the “about” signal.

void xfce_panel_plugin_menu_show_about (XfcePanelPlugin *plugin);
void xfce_panel_plugin_menu_show_configure (XfcePanelPlugin *plugin);


Plugins can save and retrieve their configuration, using a unique file name. There's one function for looking up the config file for reading and one for the file to save.

gchar *
xfce_panel_plugin_lookup_rc_file (XfcePanelPlugin *plugin);
gchar *
xfce_panel_plugin_save_location (XfcePanelPlugin *plugin,
                                 gboolean         create);

Testing and Releasing the plugin

When you test your new plugin, use the -Wall -Werror CFLAGS (and a recent version of GCC) to detect code problems. Also make sure the plugins is linked (plugin_name_LDADD in Makefile.am) to all the needed libraries, so there will be no problems when building with LDFLAGS=“-Wl,–as-needed”.

For creating a release you need to run ./autogen.sh && make distcheck. Fix all warnings and errors in make distcheck before distributing the package.

To help development, you can also test plugins without installing them on panel's prefix (e.g. /usr), you can also directly run plugins from the source so you don't need to to overwrite a plugin version from your distribution. To accomplish this, build the plugin with make and then follow these steps:

  • Create a symbolic link from your plugin binary to the panel's prefix installation, e.g. ln -s /home/johndoe/where/your/src/is/panel-plugin/.libs/libyourplugin.so /usr/lib/xfce4/panel-plugins/libyourplugin-git.so
  • Copy /usr/share/xfce4/panel/plugins/yourplugin.desktop to /usr/share/xfce4/panel/plugins/yourplugin-git.desktop
  • Edit the latter to point at 'yourplugin-git' instead of 'yourplugin', modify the Name entry to distinguish your instance and X-XFCE-Module to match the symbolic link, i.e. libyourplugin-git.
  • If you're porting a plugin to GTK+ 3, make sure to add X-XFCE-API=2.0 to the desktop-git file.

Now the 'git' version of the panel plugin should be available in the 'add plugin' panel dialog. Whenever you make changes and compile the plugin, all you need to do is to add the plugin to panel again or simply refresh the panel xfce4-panel -r.


One can use GDB and Valgrind to debug external plugins, using the technique described here.

dev/howto/panel_plugins.txt · Last modified: 2017/04/18 04:27 by andreldm