[gtkmm] Remove Gtk::WidgetCustomSnapshot

[Kjell Ahlstedt <kjellahl src gnome org>]

commit bc76eb3bdb436a2fcaf0010ca00740c1c7b28f87
Author: Kjell Ahlstedt <kjellahlstedt gmail com>
Date:   Thu Apr 19 08:56:28 2018 +0200

    Remove Gtk::WidgetCustomSnapshot
    
    The GtkWidget::draw signal has been removed. Then the GtkWidget.snapshot
    vfunc can be wrapped in Gtk::Widget like a normal vfunc. All widgets render
    themselves in the snapshot vfunc.
    The WidgetCustomSnapshot class has become unnecessary.

 gtk/gtkmm.h                       |    1 +
 gtk/gtkmm/filelist.am             |    4 +-
 gtk/gtkmm/widgetcustomsnapshot.cc |   92 -------------------------------------
 gtk/gtkmm/widgetcustomsnapshot.h  |   89 -----------------------------------
 gtk/src/widget.hg                 |    9 +---
 5 files changed, 4 insertions(+), 191 deletions(-)
---
diff --git a/gtk/gtkmm.h b/gtk/gtkmm.h
index b192715..e929d79 100644
--- a/gtk/gtkmm.h
+++ b/gtk/gtkmm.h
@@ -238,6 +238,7 @@ extern const int gtkmm_micro_version;
 #include <gtkmm/shortcutsshortcut.h>
 #include <gtkmm/shortcutswindow.h>
 #include <gtkmm/sizegroup.h>
+#include <gtkmm/snapshot.h>
 #include <gtkmm/spinbutton.h>
 #include <gtkmm/spinner.h>
 #include <gtkmm/stack.h>
diff --git a/gtk/gtkmm/filelist.am b/gtk/gtkmm/filelist.am
index ba9ed56..1b85b9f 100644
--- a/gtk/gtkmm/filelist.am
+++ b/gtk/gtkmm/filelist.am
@@ -15,8 +15,7 @@ gtkmm_files_extra_any_cc =            \
        radiobuttongroup.cc             \
        selectiondata_private.cc        \
        treemodelcolumn.cc              \
-       treeview_private.cc \
-       widgetcustomsnapshot.cc
+       treeview_private.cc
 
 gtkmm_files_extra_deprecated_cc =
 
@@ -34,7 +33,6 @@ gtkmm_files_extra_any_h =                     \
        selectiondata_private.h         \
        treemodelcolumn.h               \
        treeview_private.h              \
-       widgetcustomsnapshot.h \
        wrap_init.h
 
 gtkmm_files_extra_deprecated_h =
diff --git a/gtk/src/widget.hg b/gtk/src/widget.hg
index f140404..1d0b102 100644
--- a/gtk/src/widget.hg
+++ b/gtk/src/widget.hg
@@ -715,13 +715,8 @@ protected:
   _WRAP_VFUNC(bool contains(double x, double y) const, contains)
   _WRAP_VFUNC(Widget* pick(double x, double y), pick)
 
-  // The snapshot vfunc must not be wrapped here. It would interfere with the way
-  // gtk+ selects either the snapshot vfunc or the draw signal for rendering widgets.
-  // Custom widgets that need the snapshot vfunc must use a custom rendering widget
-  // that wraps the snapshot vfunc.
-  // https://bugzilla.gnome.org/show_bug.cgi?id=774778
-//#m4 _CONVERSION(`GtkSnapshot*',`const Glib::RefPtr<Gtk::Snapshot>&',`Glib::wrap_gtk_snapshot($3, true)')
-  //_WRAP_VFUNC(void snapshot(const Glib::RefPtr<Gtk::Snapshot>& snapshot), snapshot)
+#m4 _CONVERSION(`GtkSnapshot*',`const Glib::RefPtr<Gtk::Snapshot>&',`Glib::wrap_gtk_snapshot($3, true)')
+  _WRAP_VFUNC(void snapshot(const Glib::RefPtr<Gtk::Snapshot>& snapshot), snapshot)
 
 protected:
   _CTOR_DEFAULT()