编写 xfce4 面板插件时是否可以使用 GtkPopover

Question

我正在尝试为 xfce4 面板编写插件。它应该显示一个带有复杂容器（如 GtkBox）的弹出窗口。

我在 vala 中的代码是：

using Xfce;

public class ButtonPlugin : Xfce.PanelPlugin {
    private Gtk.MenuButton button;
    private Gtk.Popover popover;
    public override void @construct () {

        button = new Gtk.MenuButton();
        popover = new Gtk.Popover(button);

        button.set_image(
            new Gtk.Image.from_icon_name (
                "open-menu-symbolic",
                Gtk.IconSize.LARGE_TOOLBAR
            )
        );
        var menu_container = new Gtk.Box(Gtk.Orientation.VERTICAL, 0);
        menu_container.pack_start(new Gtk.Label("Hello World 1"));
        menu_container.pack_start(new Gtk.Label("Hello World 2"));
        menu_container.pack_start(new Gtk.Label("Hello World 3"));
        popover.add(menu_container);
        popover.show_all ();
        popover.hide();
        button.popover = popover;
        add (button);
        //button.show ();

        add_action_widget (button);

        save.connect (() => { message ("save yourself"); });
        free_data.connect (() => { message ("free yourself"); });
        size_changed.connect (() => { message ("panel size changed"); return false; });

        menu_show_about ();
        about.connect (() => {
                Gtk.show_about_dialog (null,
                    "program-name", "Button",
                    "comments", "Test plugin for the Xfce 4.14 Panel",
                    null);
            });
        destroy.connect (() => { Gtk.main_quit (); });
        show_all();
    }
}

[ModuleInit]
public Type xfce_panel_module_init (TypeModule module) {
    return typeof (ButtonPlugin);
}

插件启动，但点击时不显示弹出框。

是否可以使用 Popover 或者我应该切换到另一个小部件？

Answer 1

据我了解，不，弹出框在 Xfce 面板插件中不起作用。

看看这个要点：https://gist.github.com/andreldm/83c9b99e7aa133c924fb4165acc8427a

独立应用程序正确显示了弹出框，但尝试将窗口设置为与按钮一样小，弹出框没有剩余空间，这与面板插件中的问题相同。如果我没记错的话，上下文菜单可以工作，因为它们是全新的窗口，而弹出窗口不是。

在同一要点中，您可以找到与 xfce4-sample-plugin 的差异，其代码与您正在尝试的代码相似。

Answer 2

Popover 并非设计为作为独立菜单使用。 它没有自己的窗口。 必须有一个窗口，并且必须将弹出窗口附加到小部件。 假设虚拟小部件为 1x1 像素透明图像。 这是 C 中的一个独立（某种）弹出框：

#include <gtk/gtk.h> 
  

/*   save this file as standalone-popover.c
     create a 1x1 pixel transparent png image in the same folder
     and name it dummy.png
     compile with:
          gcc standalone-popover.c -o standalone-popover  `pkg-config --cflags --libs gtk+-3.0`
*/

#define DUMMY_PNG "dummy.png"


void destroy(GtkWidget* widget, gpointer data) 
{ 
    gtk_main_quit(); 
} 
  
int main(int argc, char* argv[]) 
{ 
  
    GtkWidget  *window; 
    GtkWidget  *popover;
    GtkWidget  *dummy_png_top_left;
    GtkWidget  *dummy_png_top_center;
    GtkWidget  *dummy_png_top_right;
    GtkWidget  *box;
    GtkWidget  *dummy_box_top;
    GtkWidget  *label;
    GtkWidget  *button;
    gtk_init(&argc, &argv); 
  
    window = gtk_window_new(GTK_WINDOW_TOPLEVEL); 
    gtk_window_set_type_hint (GTK_WINDOW(window),
                              GDK_WINDOW_TYPE_HINT_POPUP_MENU);
    gtk_widget_set_size_request(window, 250, 220);
    gtk_window_set_resizable (GTK_WINDOW(window), TRUE);
    gtk_window_set_keep_above (GTK_WINDOW (window), TRUE);
    gtk_window_stick (GTK_WINDOW (window));
    gtk_window_set_decorated (GTK_WINDOW(window), FALSE);
    gtk_window_set_skip_taskbar_hint (GTK_WINDOW (window), TRUE);

    gtk_widget_set_events (window, GDK_FOCUS_CHANGE_MASK);

    g_signal_connect(window, "destroy", 
                     G_CALLBACK(destroy), NULL);
    g_signal_connect (G_OBJECT (GTK_WINDOW (window)),
                    "focus-out-event",
                    G_CALLBACK (destroy),
                    NULL);
    gtk_window_present (GTK_WINDOW(window));
    gtk_container_set_border_width(GTK_CONTAINER(window), 20); 
  

    dummy_png_top_left   =  gtk_image_new_from_file (DUMMY_PNG);
    dummy_png_top_center =  gtk_image_new_from_file (DUMMY_PNG);
    dummy_png_top_right  =  gtk_image_new_from_file (DUMMY_PNG);

    dummy_box_top = gtk_box_new (GTK_ORIENTATION_HORIZONTAL, 0);
    gtk_box_set_homogeneous (GTK_BOX (dummy_box_top), TRUE);
    gtk_box_pack_start (GTK_BOX(dummy_box_top), dummy_png_top_left, TRUE, FALSE, 0);
    gtk_box_pack_start (GTK_BOX(dummy_box_top), dummy_png_top_center, TRUE, FALSE, 0);
    gtk_box_pack_start (GTK_BOX(dummy_box_top), dummy_png_top_right, TRUE, FALSE, 0);

    box = gtk_box_new (GTK_ORIENTATION_VERTICAL, 2);
    gtk_box_set_homogeneous (GTK_BOX (box), TRUE);

    gtk_widget_show(dummy_png_top_left);
    gtk_widget_show(dummy_png_top_center);
    gtk_widget_show(dummy_png_top_right);

    label = gtk_label_new ("Standalone GtkPopover");
    button = gtk_button_new_with_label("OK");
    gtk_box_pack_start (GTK_BOX(box), dummy_box_top, TRUE, TRUE, 0);
    gtk_box_pack_start (GTK_BOX(box), label, TRUE, FALSE, 10);
    gtk_box_pack_start (GTK_BOX(box), button, TRUE, FALSE, 10);

    /* here we use the dummy widget to position the popover arrows */
    popover = gtk_popover_new(dummy_png_top_center);

    gtk_container_add(GTK_CONTAINER(window), popover); 
    gtk_container_add(GTK_CONTAINER(popover), box); 
    gtk_popover_set_modal(GTK_POPOVER(popover), FALSE);

    g_signal_connect(G_OBJECT(button),
                     "clicked",
                     G_CALLBACK(destroy),
                     window);
    gtk_widget_show_all(window);

    /* need this to focus a window */
    gtk_window_present_with_time(GTK_WINDOW(window),GDK_CURRENT_TIME);
    gtk_window_activate_focus (GTK_WINDOW (window));
    gtk_widget_grab_focus(GTK_WIDGET(window));
    gtk_main(); 
  
    return 0; 
}

更复杂的是箭头。 您必须计算将窗口放置在面板插件按钮旁边的位置。 在此之上，您必须正确定位箭头，这看起来并不容易。

https://www.youtube.com/watch?v=eXZzwDDQlZ8

可能会在弹出框周围放置 8 个或更多虚拟图像，并根据面板的方向和插件在屏幕上的位置指向它们。

视频中的代码：

/*
* Copyright © 2020 misko_2083
*
* Distributed under terms of the GPL2 license.
* 
* Compile:
* gcc -Wall -s -shared -fPIC -g desktop-icons-applet.c -o desktop-icons-applet $(pkg-config --libs --cflags gtk+-3.0 libxfce4panel-2.0 libxfconf-0)
* move to lib dir (Debian 64bit here):
* mv libdicons.so /usr/lib/x86_64-linux-gnu/xfce4/panel/plugins/libdicons.so
*/

#include <libxfce4util/libxfce4util.h>
#include <libxfce4panel/xfce-panel-plugin.h>
#include <xfconf/xfconf.h>

#define DEFAULT_ICON_NAME "emblem-desktop"
#define DEFAULT_TOOLTIP_MESSAGE "Show/Hide Desktop Icons"
#define DEFAULT_TITLE "dicons"
#define XFCE_PLUGIN_VERSION "0.1"

/* change the path here to a 1 pixel transparent png */
#define DUMMY_PNG "/home/misko/Desktop/null.png"

typedef struct _DiconsPlugin {
    XfcePanelPlugin *plugin;
    GtkWidget        *button;
    GtkWidget        *icon;
    GtkWidget        *window;
    GtkWidget        *popover;
    GtkWidget        *dummy_png_top_left;
    GtkWidget        *dummy_png_top_center;
    GtkWidget        *dummy_png_top_right;
    GtkWidget        *dummy_png_bottom_left;
    GtkWidget        *dummy_png_bottom_center;
    GtkWidget        *dummy_png_bottom_right;
    gchar            *icon_name;
} DiconsPlugin;

static void
button_clicked (GtkWidget *button,
                 DiconsPlugin    *dicons);
static gboolean
on_popup_focus_out (GtkWidget *widget,
                    GdkEventFocus *event,
                    gpointer data);
                    
static gboolean
on_key_pressed (GtkWidget *widget,
                GdkEventKey *event,
                gpointer data);

static const char dicons_plugin_copyright[] =
"Copyright \xc2\xa9 2020 Miloš Pavlović\n";

static void dicons_about(XfcePanelPlugin *plugin)
{
    const gchar *auth[] = { "Miloš Pavlović", NULL };
    GdkPixbuf *icon;

    icon = xfce_panel_pixbuf_from_source("emblem-desktop", NULL, 32);
    gtk_show_about_dialog(NULL,
                  "logo", icon,
                  "license", xfce_get_license_text(XFCE_LICENSE_TEXT_GPL),
                  "version", XFCE_PLUGIN_VERSION,
                  "program-name", "dicons-applet",
                  "comments", _("Opens a configuration menu for desktop icons"),
                  "website", "https://github.com/Misko-2083",
                  "copyright", _(dicons_plugin_copyright),
                  "authors", auth,
                  NULL);
    if (icon)
        g_object_unref(G_OBJECT(icon));
}

static void
_quit_cb (GtkWidget *button, GtkWidget *window, gpointer data)
{
    (void)data; /* Avoid compiler warnings */
    
    gtk_widget_hide (window);
    
    gtk_toggle_button_set_active(GTK_TOGGLE_BUTTON(button), FALSE);
    
    return;
}

static gboolean
on_popup_focus_out (GtkWidget *widget,
                    GdkEventFocus *event,
                    gpointer data)
{
  gtk_widget_hide (widget);
  
  gtk_toggle_button_set_active(GTK_TOGGLE_BUTTON(data), FALSE);
  
  return TRUE;
}

static gboolean
on_key_pressed    (GtkWidget *widget,
                   GdkEventKey *event,
                   gpointer data)
{
    if (event->keyval == GDK_KEY_Escape){
        gtk_widget_hide (widget);
        
        gtk_toggle_button_set_active(GTK_TOGGLE_BUTTON(data), FALSE);
        
        return TRUE;
    }
    return FALSE;
}

static gboolean
on_switch_home       (GtkWidget *widget,
                   gboolean *state,
                   gpointer user_data)
{
    XfconfChannel    *channel;

    xfconf_init(NULL);
    
    channel = xfconf_channel_get("xfce4-desktop");
    
    if (state)
        xfconf_channel_set_bool(channel, "/desktop-icons/file-icons/show-home", TRUE);
    else
        xfconf_channel_set_bool(channel, "/desktop-icons/file-icons/show-home", FALSE);
        
    xfconf_shutdown();
    
    return FALSE;
}

static gboolean
on_switch_trash       (GtkWidget *widget,
                   gboolean *state,
                   gpointer user_data)
{
    XfconfChannel    *channel;

    xfconf_init(NULL);
    
    channel = xfconf_channel_get("xfce4-desktop");
    
    if (state)
        xfconf_channel_set_bool(channel, "/desktop-icons/file-icons/show-trash", TRUE);
    else
        xfconf_channel_set_bool(channel, "/desktop-icons/file-icons/show-trash", FALSE);
        
    xfconf_shutdown();
        
    return FALSE;
}

static gboolean
on_switch_filesystem       (GtkWidget *widget,
                   gboolean *state,
                   gpointer user_data)
{
    XfconfChannel    *channel;

    xfconf_init(NULL);
    
    channel = xfconf_channel_get("xfce4-desktop");
    
    if (state)
        xfconf_channel_set_bool(channel, "/desktop-icons/file-icons/show-filesystem", TRUE);
    else
        xfconf_channel_set_bool(channel, "/desktop-icons/file-icons/show-filesystem", FALSE);
        
    xfconf_shutdown();
        
    return FALSE;
}

static gboolean
on_switch_removable       (GtkWidget *widget,
                   gboolean *state,
                   gpointer user_data)
{
    XfconfChannel    *channel;

    xfconf_init(NULL);
    
    channel = xfconf_channel_get("xfce4-desktop");
    
    if (state)
        xfconf_channel_set_bool(channel, "/desktop-icons/file-icons/show-removable", TRUE);
    else
        xfconf_channel_set_bool(channel, "/desktop-icons/file-icons/show-removable", FALSE);
        
    xfconf_shutdown();
        
    return FALSE;
}

static gboolean dicons_size_changed (XfcePanelPlugin *plugin,
                     gint             size,
                     DiconsPlugin    *dicons)
{
    XfceScreenPosition position;

    position = xfce_panel_plugin_get_screen_position(plugin);
    
    if (xfce_screen_position_is_horizontal(position)) {
        /* horizontal */
        if (xfce_screen_position_is_top(position)) {
            /* top panel position */
            gtk_popover_set_relative_to(GTK_POPOVER(dicons->popover), dicons->dummy_png_top_left);
        }
        if (xfce_screen_position_is_bottom(position)) {
            /* bottom */
            gtk_popover_set_relative_to(GTK_POPOVER(dicons->popover), dicons->dummy_png_bottom_left);
        }
        if (xfce_screen_position_is_floating(position)) {
            /* floating */
            gtk_popover_set_relative_to(GTK_POPOVER(dicons->popover), dicons->dummy_png_top_left);
            /* TO DO: check if the button is in the top or bottom side
             *        of the screen and set the correct dummy widget
             */
        }
    } else {
        /* vertical */
        if (xfce_screen_position_is_left(position)) {
            /* left */
            gtk_popover_set_relative_to(GTK_POPOVER(dicons->popover), dicons->dummy_png_top_left);
        }
        if (xfce_screen_position_is_right(position)) {
            /* right */
            gtk_popover_set_relative_to(GTK_POPOVER(dicons->popover), dicons->dummy_png_top_left);
        }
        if (xfce_screen_position_is_floating(position)) {
            /* floating */
            gtk_popover_set_relative_to(GTK_POPOVER(dicons->popover), dicons->dummy_png_bottom_left);
            /* TO DO: check if the button is in the left or right side
             *        of the screen and set the correct dummy widget
             */
        }
    }

    size = size / xfce_panel_plugin_get_nrows(plugin);
    gtk_widget_set_size_request (GTK_WIDGET (plugin), size, size);
    return TRUE;
}


static void button_clicked(GtkWidget *button,
                           DiconsPlugin    *dicons)
{
    gint  x, y;

  if (gtk_toggle_button_get_active(GTK_TOGGLE_BUTTON(dicons->button)))
  {
       dicons_size_changed(dicons->plugin, xfce_panel_plugin_get_size (dicons->plugin), dicons);
       
       xfce_panel_plugin_block_autohide(dicons->plugin, TRUE);

       if (GTK_IS_TOGGLE_BUTTON (button)) {
             
           xfce_panel_plugin_position_widget(XFCE_PANEL_PLUGIN (dicons->plugin),
                                             GTK_WIDGET(dicons->window),
                                             button, &x, &y);
       } else {
           
           GdkDisplay *display = gdk_display_get_default();
           
           GdkSeat *seat = gdk_display_get_default_seat(display);
           
           GdkDevice *device = gdk_seat_get_pointer(seat);
           
           gdk_window_get_device_position(gdk_get_default_root_window(),
                                          device, &x, &y, NULL);
       }

       gtk_popover_popup(GTK_POPOVER(dicons->popover));

       gtk_toggle_button_set_active(GTK_TOGGLE_BUTTON(dicons->button), TRUE);
       
       if (!gtk_widget_get_mapped(dicons->window))
           gtk_widget_show_all(GTK_WIDGET(dicons->window));

       gtk_window_move (GTK_WINDOW(dicons->window), x, y);
       /* fix me: this function is called twice */
  } else {
      
       _quit_cb(dicons->button, dicons->window, NULL);
       if (GTK_IS_TOGGLE_BUTTON (button))
           gtk_toggle_button_set_active(GTK_TOGGLE_BUTTON(button), FALSE);
       
       xfce_panel_plugin_block_autohide(dicons->plugin, FALSE);
       gtk_popover_popdown(GTK_POPOVER(dicons->popover));

  }
}

static DiconsPlugin *dicons_init(XfcePanelPlugin *plugin)
{
    GtkWidget        *box;
    GtkWidget        *box_a;
    GtkWidget        *box_b;
    GtkWidget        *boxl;
    GtkWidget        *about_button;
    GtkWidget        *cancel_button;
    GtkWidget        *question;
    GtkWidget        *label_home;
    GtkWidget        *label_trash;
    GtkWidget        *label_filesystem;
    GtkWidget        *label_removable;
    GtkWidget        *image;
    GtkWidget        *switch_home;
    GtkWidget        *switch_trash;
    GtkWidget        *switch_filesystem;
    GtkWidget        *switch_removable;
    GdkWindow        *pwindow;
    GtkWidget        *dummy_box_top;
    GtkWidget        *dummy_box_bottom;
    XfconfChannel    *channel;

    DiconsPlugin *dicons = g_slice_new0(DiconsPlugin);

    dicons->plugin = plugin;
    dicons->icon_name = g_strdup(DEFAULT_ICON_NAME);
    dicons->button = xfce_panel_create_toggle_button();
    xfce_panel_plugin_add_action_widget (XFCE_PANEL_PLUGIN (dicons->plugin),
                                         dicons->button);
    gtk_init(NULL, NULL);

    dicons->window = gtk_window_new (GTK_WINDOW_TOPLEVEL);
    gtk_window_set_type_hint (GTK_WINDOW(dicons->window),
                              GDK_WINDOW_TYPE_HINT_POPUP_MENU);
    gtk_widget_set_size_request(dicons->window, 250, 220);
    gtk_window_set_resizable (GTK_WINDOW(dicons->window), TRUE);
    gtk_window_set_keep_above (GTK_WINDOW (dicons->window), TRUE);
    gtk_window_stick (GTK_WINDOW (dicons->window));
    gtk_window_set_skip_taskbar_hint (GTK_WINDOW (dicons->window), TRUE);
    gtk_window_set_title (GTK_WINDOW (dicons->window), "Desktop Icons");
    gtk_widget_set_events (dicons->window, GDK_FOCUS_CHANGE_MASK);
    g_signal_connect (G_OBJECT (GTK_WINDOW (dicons->window)),
                    "focus-out-event",
                    G_CALLBACK (on_popup_focus_out),
                    dicons->button);
    gtk_widget_set_events (GTK_WIDGET(dicons->window), GDK_KEY_PRESS_MASK);
    g_signal_connect (G_OBJECT (GTK_WINDOW (dicons->window)),
                    "key-press-event",
                    G_CALLBACK (on_key_pressed),
                    dicons->button);
    box = gtk_box_new (GTK_ORIENTATION_HORIZONTAL, 2);
    box_a = gtk_box_new (GTK_ORIENTATION_HORIZONTAL, 2);
    box_b = gtk_box_new (GTK_ORIENTATION_HORIZONTAL, 2);
    boxl = gtk_box_new (GTK_ORIENTATION_VERTICAL, 2);

    gtk_box_set_homogeneous (GTK_BOX (box), TRUE);

    image = gtk_image_new_from_icon_name (dicons->icon_name,
                                          GTK_ICON_SIZE_DND);
    question = gtk_label_new ("\nDesktop Icons");

    label_home = gtk_label_new ("Home");
    label_trash = gtk_label_new ("Trash");
    label_filesystem = gtk_label_new ("Filesystem");
    label_removable = gtk_label_new ("Removable");
    switch_home = gtk_switch_new ();
    switch_trash = gtk_switch_new ();
    switch_filesystem = gtk_switch_new ();
    switch_removable = gtk_switch_new ();
    
    
    g_signal_connect (G_OBJECT (switch_home),
                     "state-set",
                      G_CALLBACK (on_switch_home),
                      NULL);
    g_signal_connect (G_OBJECT (switch_trash),
                     "state-set",
                      G_CALLBACK (on_switch_trash),
                      NULL);
    g_signal_connect (G_OBJECT (switch_filesystem),
                     "state-set",
                      G_CALLBACK (on_switch_filesystem),
                      NULL);
    g_signal_connect (G_OBJECT (switch_removable),
                     "state-set",
                      G_CALLBACK (on_switch_removable),
                      NULL);
                      
    xfconf_init(NULL);
    
    channel = xfconf_channel_get("xfce4-desktop");

    /*  set initial switches */
    if (xfconf_channel_get_bool(channel, "/desktop-icons/file-icons/show-home", TRUE))
        gtk_switch_set_state (GTK_SWITCH(switch_home), TRUE);
    else
        gtk_switch_set_state (GTK_SWITCH(switch_home), FALSE);
        
    if (xfconf_channel_get_bool(channel, "/desktop-icons/file-icons/show-trash", TRUE))
        gtk_switch_set_state (GTK_SWITCH(switch_trash), TRUE);
    else
        gtk_switch_set_state (GTK_SWITCH(switch_trash), FALSE);
        
    if (xfconf_channel_get_bool(channel, "/desktop-icons/file-icons/show-filesystem", TRUE))
        gtk_switch_set_state (GTK_SWITCH(switch_filesystem), TRUE);
    else
        gtk_switch_set_state (GTK_SWITCH(switch_filesystem), FALSE);

    if (xfconf_channel_get_bool(channel, "/desktop-icons/file-icons/show-removable", TRUE))
        gtk_switch_set_state (GTK_SWITCH(switch_removable), TRUE);
    else
        gtk_switch_set_state (GTK_SWITCH(switch_removable), FALSE);

    xfconf_shutdown();
    

    dicons->dummy_png_top_left = gtk_image_new_from_file (DUMMY_PNG);
    dicons->dummy_png_top_center = gtk_image_new_from_file (DUMMY_PNG);
    dicons->dummy_png_top_right = gtk_image_new_from_file (DUMMY_PNG);

    dummy_box_top = gtk_box_new (GTK_ORIENTATION_HORIZONTAL, 0);
    gtk_box_pack_start (GTK_BOX(dummy_box_top), dicons->dummy_png_top_left, TRUE, FALSE, 0);
    gtk_box_pack_start (GTK_BOX(dummy_box_top), dicons->dummy_png_top_center, TRUE, FALSE, 0);
    gtk_box_pack_start (GTK_BOX(dummy_box_top), dicons->dummy_png_top_right, TRUE, FALSE, 0);
    
    dicons->dummy_png_bottom_left = gtk_image_new_from_file (DUMMY_PNG);
    dicons->dummy_png_bottom_center = gtk_image_new_from_file (DUMMY_PNG);
    dicons->dummy_png_bottom_right = gtk_image_new_from_file (DUMMY_PNG);

    dummy_box_bottom = gtk_box_new (GTK_ORIENTATION_HORIZONTAL, 0);
    gtk_box_pack_start (GTK_BOX(dummy_box_bottom), dicons->dummy_png_bottom_left, TRUE, FALSE, 0);
    gtk_box_pack_start (GTK_BOX(dummy_box_bottom), dicons->dummy_png_bottom_center, TRUE, FALSE, 0);
    gtk_box_pack_start (GTK_BOX(dummy_box_bottom), dicons->dummy_png_bottom_right, TRUE, FALSE, 0);

    gtk_widget_show(dicons->dummy_png_top_left);
    gtk_widget_show(dicons->dummy_png_top_center);
    gtk_widget_show(dicons->dummy_png_top_right);
    gtk_widget_show(dicons->dummy_png_bottom_left);
    gtk_widget_show(dicons->dummy_png_bottom_center);
    gtk_widget_show(dicons->dummy_png_bottom_right);

    dicons->popover = gtk_popover_new(dicons->dummy_png_top_left);
    gtk_popover_set_constrain_to(GTK_POPOVER(dicons->popover), GTK_POPOVER_CONSTRAINT_NONE);

    /* modal blocks the panel preferences process,
     *  it needs to be set to FALSE */
    gtk_popover_set_modal(GTK_POPOVER(dicons->popover), FALSE);
    
    gtk_container_add(GTK_CONTAINER(dicons->window), dicons->popover);
    gtk_container_add(GTK_CONTAINER(dicons->popover), boxl);


    gtk_box_pack_start (GTK_BOX(box_a), label_home, TRUE, TRUE, 10);
    gtk_box_pack_start (GTK_BOX(box_a), switch_home, FALSE, TRUE, 10);
    gtk_box_pack_start (GTK_BOX(box_a), label_trash, TRUE, TRUE, 10);
    gtk_box_pack_start (GTK_BOX(box_a), switch_trash, FALSE, TRUE, 10);
    gtk_box_pack_start (GTK_BOX(box_b), label_filesystem, TRUE, TRUE, 10);
    gtk_box_pack_start (GTK_BOX(box_b), switch_filesystem, FALSE, TRUE, 10);
    gtk_box_pack_start (GTK_BOX(box_b), label_removable, TRUE, TRUE, 10);
    gtk_box_pack_start (GTK_BOX(box_b), switch_removable, FALSE, TRUE, 10);

    about_button = gtk_button_new_with_label("About");
    cancel_button = gtk_button_new_with_label("Cancel");
    
    g_signal_connect(G_OBJECT(cancel_button),
                     "clicked",
                     G_CALLBACK(_quit_cb),
                     dicons->window);
    g_signal_connect(G_OBJECT(about_button),
                     "clicked",
                     G_CALLBACK(dicons_about),
                     plugin);

    gtk_box_pack_start (GTK_BOX(boxl), dummy_box_top, TRUE, TRUE, 0);

    gtk_box_pack_start (GTK_BOX(boxl), image, TRUE, TRUE, 0);
    gtk_box_pack_start (GTK_BOX(boxl), question, TRUE, TRUE, 0);

    gtk_box_pack_start (GTK_BOX(boxl), box_a, FALSE, TRUE, 5);
    gtk_box_pack_start (GTK_BOX(boxl), box_b, FALSE, TRUE, 5);
    
    gtk_box_pack_start (GTK_BOX(box), about_button, TRUE, TRUE, 10);
    gtk_box_pack_start (GTK_BOX (box), cancel_button, TRUE, TRUE, 10);
    gtk_box_pack_start (GTK_BOX(boxl), box, TRUE, TRUE, 10);
    
    gtk_box_pack_end (GTK_BOX(boxl), dummy_box_bottom, TRUE, TRUE, 0);
    gtk_window_set_decorated (GTK_WINDOW(dicons->window), FALSE);
    gtk_widget_show(dicons->button);
    
    /*gtk_window_set_attached_to(GTK_WINDOW(dicons->window),
                               dicons->button);*/
    pwindow = gtk_widget_get_parent_window(dicons->button);
    
    gtk_window_set_transient_for(GTK_WINDOW(dicons->window),
                                 GTK_WINDOW(pwindow));

    g_signal_connect(G_OBJECT(dicons->button), "toggled",
             G_CALLBACK(button_clicked), dicons);
    gtk_widget_set_tooltip_text (GTK_WIDGET(dicons->button),
                                 DEFAULT_TOOLTIP_MESSAGE);
    dicons->icon = xfce_panel_image_new_from_source(dicons->icon_name);
    gtk_widget_show(dicons->icon);
    gtk_container_add(GTK_CONTAINER(dicons->button), dicons->icon);

    return dicons;
}

static void dicons_free(XfcePanelPlugin *plugin, DiconsPlugin *dicons)
{
    gtk_widget_destroy(dicons->button);
    
    gtk_widget_destroy(dicons->icon);
    
    if (GTK_IS_WIDGET (dicons->window))
        gtk_widget_destroy(dicons->window);

    if (GTK_IS_WIDGET (dicons->popover))
        gtk_widget_destroy(dicons->popover);

    g_slice_free(DiconsPlugin, dicons);
}

static void set_button_active (GtkToggleButton *button)
{
     if (GTK_IS_TOGGLE_BUTTON(button)) {
     
         if (!gtk_toggle_button_get_active(button)) {
              gtk_toggle_button_set_active(button, TRUE);
             }
         else
             {
              gtk_toggle_button_set_active(button, FALSE);
             }
     }
}

static gboolean dicons_remote (XfcePanelPlugin *plugin,
                             gchar           *name,
                             GValue          *value,
                             DiconsPlugin    *dicons)
{
    g_return_val_if_fail (value == NULL || G_IS_VALUE (value), FALSE);
    
    if (strcmp (name, "popup") == 0
        && !gtk_toggle_button_get_active(GTK_TOGGLE_BUTTON(dicons->button)) 
        &&  gtk_widget_get_visible (GTK_WIDGET (plugin)) )
        {
        if (value != NULL
            && G_VALUE_HOLDS_BOOLEAN (value)
            && g_value_get_boolean (value))
            {
              set_button_active(GTK_TOGGLE_BUTTON(dicons->button));
                /* popup here at mouse pointer , where X is an internal id
                 * xfce4-panel --plugin-event=desktop-icons-applet-X:popup:bool:true
                 */
              button_clicked(NULL, dicons);
            }
        else
            {   
                set_button_active(GTK_TOGGLE_BUTTON(dicons->button));
                /* popup here, where X is an internal id
                 * xfce4-panel --plugin-event=desktop-icons-applet-X:popup:bool:false
                 */
              button_clicked(dicons->button, dicons);
            }
       return TRUE;

        }
    return FALSE;
}


static void dicons_construct(XfcePanelPlugin *plugin)
{
    DiconsPlugin *dicons;
    
    dicons = dicons_init(plugin);
    
    gtk_container_add(GTK_CONTAINER(plugin), dicons->button);
    
    xfce_panel_plugin_add_action_widget(plugin, dicons->button);
    
    xfce_panel_plugin_menu_show_about(plugin);
    
    g_signal_connect (G_OBJECT(plugin),
                     "free-data",
                     G_CALLBACK(dicons_free), dicons);
    g_signal_connect (G_OBJECT(plugin),
                     "size-changed",
                     G_CALLBACK(dicons_size_changed), dicons);
    g_signal_connect (G_OBJECT (plugin),
                     "remote-event",
                     G_CALLBACK(dicons_remote), dicons);
    g_signal_connect (G_OBJECT (plugin),
                     "about",
                    G_CALLBACK (dicons_about), dicons);
}
XFCE_PANEL_PLUGIN_REGISTER(dicons_construct);

还有桌面文件 /usr/share/xfce4/panel/plugins/desktop-icons-applet.desktop

[Xfce Panel]
Type=X-XFCE-PanelPlugin
Encoding=UTF-8
Name=Desktop Icons
Comment=Show and Hide desktop icons
Icon=emblem-desktop
X-XFCE-Module=dicons
X-XFCE-Internal=true
X-XFCE-Unique=false
X-XFCE-API=2.0