constraints: account for decorations when positioning modal dialogs

What we want to achieve is that the dialog is visually centered
on the parent, including the decorations for both, and making sure
that CSD/frame_extents are respected.

https://bugzilla.gnome.org/show_bug.cgi?id=707194

1 files changed, 17 insertions, 7 deletions

diff --git a/src/core/constraints.c b/src/core/constraints.c
index db4e8d67..dda3350a 100644
--- a/src/core/constraints.c
+++ b/src/core/constraints.c
@@ -822,18 +822,28 @@ constrain_modal_dialog (MetaWindow         *window,
 {
   int x, y;
   MetaWindow *parent = meta_window_get_transient_for (window);
+  MetaRectangle child_rect, parent_rect;
   gboolean constraint_already_satisfied;
 
   if (!meta_window_is_attached_dialog (window))
     return TRUE;
 
-  x = parent->rect.x + (parent->rect.width / 2 - info->current.width / 2);
-  y = parent->rect.y + (parent->rect.height / 2 - info->current.height / 2);
-  if (parent->frame)
-    {
-      x += parent->frame->rect.x;
-      y += parent->frame->rect.y;
-   }
+  /* We want to center the dialog on the parent, including the decorations
+     for both of them. info->current is in client X window coordinates, so we need
+     to convert them to frame coordinates, apply the centering and then
+     convert back to client.
+  */
+
+  child_rect = info->current;
+  extend_by_frame (window, &child_rect, info->borders);
+
+  meta_window_get_outer_rect (parent, &parent_rect);
+
+  child_rect.x = parent_rect.x + (parent_rect.width / 2 - child_rect.width / 2);
+  child_rect.y = parent_rect.y + (parent_rect.height / 2 - child_rect.height / 2);
+  unextend_by_frame (window, &child_rect, info->borders);
+  x = child_rect.x;
+  y = child_rect.y;
 
   constraint_already_satisfied = (x == info->current.x) && (y == info->current.y);