[gparted] port-to-gtk3: Use Gdk::AppLaunchContext to launch yelp (#7)

[Mike Fleetwood <mfleetwo src gnome org>]

commit 2953778a4c0e61d8fe49c7a6d707add8a9eb0634
Author: Luca Bacci <luca bacci982 gmail com>
Date:   Thu Aug 9 10:26:44 2018 +0200

    port-to-gtk3: Use Gdk::AppLaunchContext to launch yelp (#7)
    
    gdk_spawn_command_line_on_screen() is not present in Gtk3.  The
    documentation from Gtkmm 2.24 states [1]:
    
        gdk_spawn_command_line_on_screen has been deprecated since version
        2.24 and should not be used in newly-written code.  This function is
        being removed in 3.0.  Use either g_spawn_command_line_sync(),
        g_spawn_command_line_async() or GdkAppLaunchContext instead.
    
    g_spawn_command_line_sync() and g_spawn_command_line_async() are screen
    / display agnostic, as such we would loose functionality.  There is a
    workaround, which involves setting the DISPLAY environment variable [2],
    but it's a weak solution (and I don't know if it works on backends
    other than X11).
    
    GdkAppLaunchContext is an implementation of GIO's GAppLaunchContext that
    handles launching an application in a graphical context [3].  Therefore
    use GdkAppLaunchContext and GIO's GAppInfo.
    
    GdkAppLaunchContext was introduced in Gtk2 version 2.14.  The C++
    wrapper Gdk::AppLaunchContext was introduced only in Gtkmm3 version 3.4
    [4].  Bump the minimum required version of Gtkmm to 3.4.0 for this
    requirement.
    
    GAppInfo was introduced in GLib version 2.16.  The C++ wrapper
    Gio::AppInfo was introduced in Giomm version 2.16.  Note that the
    minimum required version for glibmm is already 2.32.
    
    [1] GDK 2 Reference Manual, GdkScreen, gdk_spawn_on_screen()
        https://developer.gnome.org/gdk2/2.24/GdkScreen.html#gdk-spawn-on-screen
    
    [2] Migrating from GTK+ 2.x to GTK+ 3 - "Use GIO for launching applications"
        https://developer.gnome.org/gtk3/stable/gtk-migrating-2-to-3.html#id-1.6.3.3.7
    
    [3] GDK 3 Reference Manual - "Application launching"
        https://developer.gnome.org/gdk3/stable/gdk3-Application-launching.html
    
    [4] Gtkmm 3.4 Gdk::AppLaunchContext Class Reference, Detailed Description
        https://developer.gnome.org/gtkmm/3.4/classGdk_1_1AppLaunchContext.html#details
    
    Closes #7 - Port to Gtk3

 configure.ac       |  2 +-
 src/Win_GParted.cc | 50 +++++++++++++++++++++++++++++++++-----------------
 2 files changed, 34 insertions(+), 18 deletions(-)
---
diff --git a/configure.ac b/configure.ac
index 9c11ab79..8cad5e8e 100644
--- a/configure.ac
+++ b/configure.ac
@@ -199,7 +199,7 @@ AC_SUBST([GTHREAD_LIBS])
 AC_SUBST([GTHREAD_CFLAGS])
 
 dnl GTKMM
-PKG_CHECK_MODULES([GTKMM], [gtkmm-3.0 >= 3.0.0])
+PKG_CHECK_MODULES([GTKMM], [gtkmm-3.0 >= 3.4.0])
 AC_SUBST([GTKMM_LIBS])
 AC_SUBST([GTKMM_CFLAGS])
 
diff --git a/src/Win_GParted.cc b/src/Win_GParted.cc
index a30329ba..ea29baa7 100644
--- a/src/Win_GParted.cc
+++ b/src/Win_GParted.cc
@@ -1748,28 +1748,44 @@ void Win_GParted::show_help_dialog( const Glib::ustring & filename /* E.g., gpar
                uri = uri + "?" + link_id ;
        }
 
-       gscreen = gdk_screen_get_default() ;
-
+       gscreen = get_window()->get_screen()->gobj();
        gtk_show_uri( gscreen, uri .c_str(), gtk_get_current_event_time(), &error ) ;
        if ( error != NULL )
        {
                //Try opening yelp application directly
-               g_clear_error( &error );  // Clear error from trying to open gparted help manual above 
(gtk_show_uri).
-               Glib::ustring command = "yelp " + uri ;
-               gdk_spawn_command_line_on_screen( gscreen, command .c_str(), &error ) ;
-       }
 
-       if ( error != NULL )
-       {
-               Gtk::MessageDialog dialog( *this
-                                        , _( "Unable to open GParted Manual help file" )
-                                        , false
-                                        , Gtk::MESSAGE_ERROR
-                                        , Gtk::BUTTONS_OK
-                                        , true
-                                        ) ;
-               dialog .set_secondary_text( error ->message ) ;
-               dialog .run() ;
+               Glib::RefPtr<Gio::AppInfo> yelp
+                       = Gio::AppInfo::create_from_commandline("yelp", "", 
Gio::APP_INFO_CREATE_SUPPORTS_URIS);
+
+               Glib::RefPtr<Gdk::AppLaunchContext> context
+                       = get_window()->get_display()->get_app_launch_context();
+
+               context->set_timestamp(gtk_get_current_event_time());
+
+               bool launched;
+               try
+               {
+                       launched = yelp->launch_uris(std::vector<std::string>(1, uri), context);
+               }
+               catch (Glib::Error& e)
+               {
+                       std::cerr << e.what() << std::endl;
+                       launched = false;
+               }
+
+               if (!launched)
+               {
+                       Gtk::MessageDialog dialog(*this,
+                                                 _( "Unable to open GParted Manual help file" ),
+                                                 false,
+                                                 Gtk::MESSAGE_ERROR,
+                                                 Gtk::BUTTONS_OK,
+                                                 true);
+                       dialog.set_secondary_text(error->message);
+                       dialog.run();
+               }
+
+               g_clear_error(&error);
        }
 }