[gtk+] Fix calculation of edge input window size in case the real window is too small.

[Emmanuele Bassi <ebassi src gnome org>]

commit 3c9cca596fac6c5e72f7d6147eeb78f16be549dd
Author: Christoph Reiter <reiter christoph gmail com>
Date:   Sat Jun 20 13:27:20 2015 +0200

    Fix calculation of edge input window size in case the real window is too small.
    
    This error resulted in warnings like
    "pixman_region32_init_rect: Invalid rectangle passed"
    
    In case the window is smaller than handle_size * 2 the resulting
    edge window got a negative size. Prevent that by limiting the
    handle size to half the respective edge length. This also
    prevents the corner windows from overlapping in case the window
    is too small.

 gtk/gtkwindow.c |   59 ++++++++++++++++++++++++++++--------------------------
 1 files changed, 31 insertions(+), 28 deletions(-)
---
diff --git a/gtk/gtkwindow.c b/gtk/gtkwindow.c
index a8ebf5c..06eee67 100644
--- a/gtk/gtkwindow.c
+++ b/gtk/gtkwindow.c
@@ -6642,7 +6642,7 @@ update_border_windows (GtkWindow *window)
   GtkWidget *widget = (GtkWidget *)window;
   GtkWindowPrivate *priv = window->priv;
   gboolean resize_h, resize_v;
-  gint handle;
+  gint handle, handle_h, handle_v;
   cairo_region_t *region;
   cairo_rectangle_int_t rect;
   gint width, height;
@@ -6696,30 +6696,33 @@ update_border_windows (GtkWindow *window)
   width = gtk_widget_get_allocated_width (widget) - (window_border.left + window_border.right);
   height = gtk_widget_get_allocated_height (widget) - (window_border.top + window_border.bottom);
 
+  handle_h = MIN (handle, width / 2);
+  handle_v = MIN (handle, height / 2);
+
   if (resize_h && resize_v)
     {
       gdk_window_move_resize (priv->border_window[GDK_WINDOW_EDGE_NORTH_WEST],
                               window_border.left - border.left, window_border.top - border.top,
-                              border.left + handle, border.top + handle);
+                              border.left + handle_h, border.top + handle_v);
       gdk_window_move_resize (priv->border_window[GDK_WINDOW_EDGE_NORTH_EAST],
-                              window_border.left + width - handle, window_border.top - border.top,
-                              border.right + handle, border.top + handle);
+                              window_border.left + width - handle_h, window_border.top - border.top,
+                              border.right + handle_h, border.top + handle_v);
       gdk_window_move_resize (priv->border_window[GDK_WINDOW_EDGE_SOUTH_WEST],
-                              window_border.left - border.left, window_border.top + height - handle,
-                              border.left + handle, border.bottom + handle);
+                              window_border.left - border.left, window_border.top + height - handle_v,
+                              border.left + handle_h, border.bottom + handle_v);
       gdk_window_move_resize (priv->border_window[GDK_WINDOW_EDGE_SOUTH_EAST],
-                              window_border.left + width - handle, window_border.top + height - handle,
-                              border.right + handle, border.bottom + handle);
+                              window_border.left + width - handle_h, window_border.top + height - handle_v,
+                              border.right + handle_h, border.bottom + handle_v);
 
       rect.x = 0;
       rect.y = 0;
-      rect.width = border.left + handle;
-      rect.height = border.top + handle;
+      rect.width = border.left + handle_h;
+      rect.height = border.top + handle_v;
       region = cairo_region_create_rectangle (&rect);
       rect.x = border.left;
       rect.y = border.top;
-      rect.width = handle;
-      rect.height = handle;
+      rect.width = handle_h;
+      rect.height = handle_v;
       cairo_region_subtract_rectangle (region, &rect);
       gdk_window_shape_combine_region (priv->border_window[GDK_WINDOW_EDGE_NORTH_WEST],
                                        region, 0, 0);
@@ -6727,13 +6730,13 @@ update_border_windows (GtkWindow *window)
 
       rect.x = 0;
       rect.y = 0;
-      rect.width = border.right + handle;
-      rect.height = border.top + handle;
+      rect.width = border.right + handle_h;
+      rect.height = border.top + handle_v;
       region = cairo_region_create_rectangle (&rect);
       rect.x = 0;
       rect.y = border.top;
-      rect.width = handle;
-      rect.height = handle;
+      rect.width = handle_h;
+      rect.height = handle_v;
       cairo_region_subtract_rectangle (region, &rect);
       gdk_window_shape_combine_region (priv->border_window[GDK_WINDOW_EDGE_NORTH_EAST],
                                        region, 0, 0);
@@ -6741,13 +6744,13 @@ update_border_windows (GtkWindow *window)
 
       rect.x = 0;
       rect.y = 0;
-      rect.width = border.left + handle;
-      rect.height = border.bottom + handle;
+      rect.width = border.left + handle_h;
+      rect.height = border.bottom + handle_v;
       region = cairo_region_create_rectangle (&rect);
       rect.x = border.left;
       rect.y = 0;
-      rect.width = handle;
-      rect.height = handle;
+      rect.width = handle_h;
+      rect.height = handle_v;
       cairo_region_subtract_rectangle (region, &rect);
       gdk_window_shape_combine_region (priv->border_window[GDK_WINDOW_EDGE_SOUTH_WEST],
                                        region, 0, 0);
@@ -6755,13 +6758,13 @@ update_border_windows (GtkWindow *window)
 
       rect.x = 0;
       rect.y = 0;
-      rect.width = border.right + handle;
-      rect.height = border.bottom + handle;
+      rect.width = border.right + handle_h;
+      rect.height = border.bottom + handle_v;
       region = cairo_region_create_rectangle (&rect);
       rect.x = 0;
       rect.y = 0;
-      rect.width = handle;
-      rect.height = handle;
+      rect.width = handle_h;
+      rect.height = handle_v;
       cairo_region_subtract_rectangle (region, &rect);
       gdk_window_shape_combine_region (priv->border_window[GDK_WINDOW_EDGE_SOUTH_EAST],
                                        region, 0, 0);
@@ -6786,8 +6789,8 @@ update_border_windows (GtkWindow *window)
 
       if (resize_h)
         {
-          x = window_border.left + handle;
-          w = width - 2 * handle;
+          x = window_border.left + handle_h;
+          w = width - 2 * handle_h;
         }
       else
         {
@@ -6817,8 +6820,8 @@ update_border_windows (GtkWindow *window)
 
       if (resize_v)
         {
-          y = window_border.top + handle;
-          h = height - 2 * handle;
+          y = window_border.top + handle_v;
+          h = height - 2 * handle_v;
         }
       else
         {