gtkwindow: Only allow unrestricted positioning to text handle popovers

This behavior has been made optional on add_popover() time, text handles
will keep being able to overflow the window, in order to allow text
selection on views too close to the window edge.

Regular GtkPopovers are reinstaurated to the previous size positioning
logic though, that is, limited by the visible area of the window.

gtk/gtkpopover.c

@@ -1699,7 +1699,7 @@ _gtk_popover_parent_hierarchy_changed (GtkWidget  *widget,
     _gtk_window_remove_popover (priv->window, GTK_WIDGET (popover));
 
   if (new_window)
-    _gtk_window_add_popover (new_window, GTK_WIDGET (popover), priv->widget);
+    _gtk_window_add_popover (new_window, GTK_WIDGET (popover), priv->widget, TRUE);
 
   priv->window = new_window;
 
@@ -1970,7 +1970,7 @@ gtk_popover_update_relative_to (GtkPopover *popover,
     }
 
   if (priv->window)
-    _gtk_window_add_popover (priv->window, GTK_WIDGET (popover), priv->widget);
+    _gtk_window_add_popover (priv->window, GTK_WIDGET (popover), priv->widget, TRUE);
 
   if (relative_to)
     scrollable = GTK_SCROLLABLE (gtk_widget_get_ancestor (priv->widget, GTK_TYPE_SCROLLABLE));

gtk/gtktexthandle.c

@@ -307,7 +307,7 @@ _gtk_text_handle_ensure_widget (GtkTextHandle         *handle,
 
       priv->windows[pos].widget = g_object_ref_sink (widget);
       window = gtk_widget_get_ancestor (priv->parent, GTK_TYPE_WINDOW);
-      _gtk_window_add_popover (GTK_WINDOW (window), widget, priv->parent);
+      _gtk_window_add_popover (GTK_WINDOW (window), widget, priv->parent, FALSE);
 
       gtk_style_context_set_parent (gtk_widget_get_style_context (widget),
                                     gtk_widget_get_style_context (priv->parent));

gtk/gtkwindow.c

@@ -143,6 +143,7 @@ struct _GtkWindowPopover
   GtkPositionType pos;
   cairo_rectangle_int_t rect;
   gulong unmap_id;
+  guint clamp_allocation : 1;
 };
 
 struct _GtkWindowPrivate
@@ -6356,6 +6357,7 @@ popover_get_rect (GtkWindowPopover      *popover,
   GtkAllocation win_alloc;
   GtkRequisition req;
   GtkBorder win_border;
+  gdouble min, max;
 
   gtk_widget_get_preferred_size (popover->widget, NULL, &req);
   gtk_widget_get_allocation (GTK_WIDGET (window), &win_alloc);
@@ -6378,8 +6380,19 @@ popover_get_rect (GtkWindowPopover      *popover,
           rect->height = win_alloc.height;
         }
       else
-        rect->y = CLAMP (popover->rect.y + (popover->rect.height / 2) -
+        {
-                         (req.height / 2), 0, win_alloc.y + win_alloc.height + win_border.bottom - req.height);
+          min = 0;
+          max = win_alloc.y + win_alloc.height + win_border.bottom - req.height;
+
+          if (popover->clamp_allocation)
+            {
+              min += win_border.top;
+              max -= win_border.bottom;
+            }
+
+          rect->y = CLAMP (popover->rect.y + (popover->rect.height / 2) -
+                           (req.height / 2), min, max);
+        }
 
       if ((popover->pos == GTK_POS_LEFT) ==
           (gtk_widget_get_direction (popover->widget) == GTK_TEXT_DIR_LTR))
@@ -6410,8 +6423,19 @@ popover_get_rect (GtkWindowPopover      *popover,
           rect->width = win_alloc.width;
         }
       else
-        rect->x = CLAMP (popover->rect.x + (popover->rect.width / 2) -
+        {
-                         (req.width / 2), 0, win_alloc.x + win_alloc.width + win_border.right - req.width);
+          min = 0;
+          max = win_alloc.x + win_alloc.width + win_border.right - req.width;
+
+          if (popover->clamp_allocation)
+            {
+              min += win_border.left;
+              max -= win_border.right;
+            }
+
+          rect->x = CLAMP (popover->rect.x + (popover->rect.width / 2) -
+                           (req.width / 2), min, max);
+        }
 
       if (popover->pos == GTK_POS_TOP)
         {
@@ -11822,7 +11846,8 @@ _gtk_window_get_shadow_width (GtkWindow *window,
 void
 _gtk_window_add_popover (GtkWindow *window,
                          GtkWidget *popover,
-                         GtkWidget *parent)
+                         GtkWidget *parent,
+                         gboolean   clamp_allocation)
 {
   GtkWindowPrivate *priv;
   GtkWindowPopover *data;
@@ -11842,6 +11867,7 @@ _gtk_window_add_popover (GtkWindow *window,
   data = g_new0 (GtkWindowPopover, 1);
   data->widget = popover;
   data->parent = parent;
+  data->clamp_allocation = !!clamp_allocation;
   priv->popovers = g_list_prepend (priv->popovers, data);
 
   if (gtk_widget_get_realized (GTK_WIDGET (window)))

gtk/gtkwindowprivate.h

@@ -105,7 +105,8 @@ void            _gtk_window_set_window_group (GtkWindow      *window,
 /* Popovers */
 void    _gtk_window_add_popover          (GtkWindow                   *window,
                                           GtkWidget                   *popover,
-                                          GtkWidget                   *popover_parent);
+                                          GtkWidget                   *popover_parent,
+                                          gboolean                     clamp_allocation);
 void    _gtk_window_remove_popover       (GtkWindow                   *window,
                                           GtkWidget                   *popover);
 void    _gtk_window_set_popover_position (GtkWindow                   *window,