Change semantics of the draw signal

Previously, we tried to move the context's origin to the widget's top
left location, no matter what window the paint was happening on. Now we
only do that for child windows of the widget's window and leave the
context untouched for windows that the widget has created outside its
own hierarchy. In those casses, we also don't clip the context to
the widget's allocation.

Includes fixes to GtkHandlebox for this effect and fixes all known
issues with it.

These semantics assume that gtk_widget_draw() should only draw the parts
of a widget that are inside child windows and not draw stuff that is
located in completely different GdkWindows. In the handlebox case, it
means that it should only draw the handle when it is attached, but not
when it isn't. We'll likely need a special draw function for the
detached handlebox if we want to draw it.

gtk/gtkhandlebox.c

@@ -927,20 +927,13 @@ gtk_handle_box_paint (GtkWidget      *widget,
   GtkHandleBoxPrivate *priv = hb->priv;
   GtkBin *bin = GTK_BIN (widget);
   GtkWidget *child;
-  gint x, y, width, height;
+  gint width, height;
   GdkRectangle rect;
   gint handle_position;
   GtkOrientation handle_orientation;
 
   handle_position = effective_handle_position (hb);
 
-  cairo_save (cr);
-
-  gdk_window_get_origin (gtk_widget_get_window (widget), &x, &y);
-  cairo_translate (cr, -x, -y);
-  gdk_window_get_origin (priv->bin_window, &x, &y);
-  cairo_translate (cr, x, y);
-
   gdk_drawable_get_size (priv->bin_window, &width, &height);
 
   gtk_cairo_paint_box (gtk_widget_get_style (widget),
@@ -991,8 +984,6 @@ gtk_handle_box_paint (GtkWidget      *widget,
                     rect.x, rect.y, rect.width, rect.height, 
                     handle_orientation);
 
-  cairo_restore (cr);
-
   child = gtk_bin_get_child (bin);
   if (child != NULL && gtk_widget_get_visible (child))
     GTK_WIDGET_CLASS (gtk_handle_box_parent_class)->draw (widget, cr);
@@ -1010,8 +1001,7 @@ gtk_handle_box_draw (GtkWidget *widget,
       if (priv->child_detached)
         gtk_handle_box_draw_ghost (hb, cr);
     }
-
-  if (gtk_cairo_should_draw_window (cr, priv->bin_window))
+  else if (gtk_cairo_should_draw_window (cr, priv->bin_window))
     gtk_handle_box_paint (widget, cr);
   
   return FALSE;

gtk/gtkwidget.c

@@ -5124,16 +5124,20 @@ gtk_cairo_should_draw_window (cairo_t *cr,
  */
 void
 _gtk_widget_draw_internal (GtkWidget *widget,
-                           cairo_t   *cr)
+                           cairo_t   *cr,
+                           gboolean   clip_to_size)
 {
   if (!gtk_widget_is_drawable (widget))
     return;
 
-  cairo_rectangle (cr, 
-                   0, 0,
-                   widget->priv->allocation.width,
-                   widget->priv->allocation.height);
-  cairo_clip (cr);
+  if (clip_to_size)
+    {
+      cairo_rectangle (cr, 
+                       0, 0,
+                       widget->priv->allocation.width,
+                       widget->priv->allocation.height);
+      cairo_clip (cr);
+    }
 
   if (gdk_cairo_get_clip_rectangle (cr, NULL))
     {
@@ -5149,9 +5153,10 @@ static gboolean
 gtk_widget_real_expose_event (GtkWidget      *widget,
 			      GdkEventExpose *expose)
 {
-  GdkWindow *window;
+  GdkWindow *window, *w;
   gboolean result = FALSE;
   cairo_t *cr;
+  int x, y;
 
   if (!gtk_widget_is_drawable (widget))
     return FALSE;
@@ -5162,37 +5167,32 @@ gtk_widget_real_expose_event (GtkWidget      *widget,
   gdk_cairo_region (cr, expose->region);
   cairo_clip (cr);
 
-  /* translate cairo context properly */
-  window = gtk_widget_get_window (widget);
-  if (window != expose->window)
-    {
-      int x, y;
-
-      if (gdk_window_get_parent (expose->window) == window)
-        {
-          gdk_window_get_position (expose->window, &x, &y);
-        }
-      else
-        {
-          int ex, ey;
-          gdk_window_get_origin (expose->window, &ex, &ey);
-          gdk_window_get_origin (window, &x, &y);
-          x = ex - x;
-          y = ey - y;
-        }
-
-      cairo_translate (cr, -x, -y);
-    }
-
-
   if (!gtk_widget_get_has_window (widget))
     {
-      cairo_translate (cr,
-                       widget->priv->allocation.x,
-                       widget->priv->allocation.y);
+      x = widget->priv->allocation.x;
+      y = widget->priv->allocation.y;
+    }
+  else
+    {
+      x = 0;
+      y = 0;
     }
 
-  _gtk_widget_draw_internal (widget, cr);
+  /* translate cairo context properly */
+  window = gtk_widget_get_window (widget);
+
+  for (w = expose->window; w && w != window; w = gdk_window_get_parent (w))
+    {
+      int wx, wy;
+      gdk_window_get_position (w, &wx, &wy);
+      x -= wx;
+      y -= wy;
+    }
+
+  if (w)
+    cairo_translate (cr, x, y);
+
+  _gtk_widget_draw_internal (widget, cr, w != NULL);
 
   /* unset here, so if someone keeps a reference to cr we
    * don't leak the window. */

gtk/gtkwidget.h

@@ -950,7 +950,8 @@ void            gtk_requisition_free     (GtkRequisition       *requisition);
 GdkEventExpose *  _gtk_cairo_get_event                    (cairo_t      *cr);
 
 void              _gtk_widget_draw_internal               (GtkWidget    *widget,
-                                                           cairo_t      *cr);
+                                                           cairo_t      *cr,
+                                                           gboolean      clip_to_size);
 void              _gtk_widget_set_has_default             (GtkWidget    *widget,
                                                            gboolean      has_default);
 void              _gtk_widget_set_has_grab                (GtkWidget    *widget,