Dragging panels near screen edge

ash/wm/panels/panel_window_resizer.cc

Index: ash/wm/panels/panel_window_resizer.cc
diff --git a/ash/wm/panels/panel_window_resizer.cc b/ash/wm/panels/panel_window_resizer.cc
index 1c054b4c36f20c00128ae0d763a53588d1e62589..e88cd1937e6d78ff5afba2fb585ac2ad885b5b6b 100644
--- a/ash/wm/panels/panel_window_resizer.cc
+++ b/ash/wm/panels/panel_window_resizer.cc
@@ -64,13 +64,11 @@ void PanelWindowResizer::Drag(const gfx::Point& location, int event_flags) {
     did_move_or_resize_ = true;
     StartedDragging();
   }
-  gfx::Point location_in_screen = location;
-  wm::ConvertPointToScreen(GetTarget()->parent(), &location_in_screen);
 
   // Check if the destination has changed displays.
   gfx::Screen* screen = Shell::GetScreen();
   const gfx::Display dst_display =
-      screen->GetDisplayNearestPoint(location_in_screen);
+      screen->GetDisplayNearestPoint(last_location_);
   if (dst_display.id() !=
       screen->GetDisplayNearestWindow(panel_container_->GetRootWindow()).id()) {
     // The panel is being dragged to a new display. If the previous container is
@@ -198,9 +196,11 @@ void PanelWindowResizer::StartedDragging() {
     // Attach the panel while dragging placing it in front of other panels.
     GetTarget()->SetProperty(internal::kContinueDragAfterReparent, true);
     GetTarget()->SetProperty(internal::kPanelAttachedKey, true);
-    GetTarget()->SetDefaultParentByRootWindow(
-        GetTarget()->GetRootWindow(),
-        GetTarget()->GetBoundsInScreen());
+    gfx::Point start_location_in_screen(GetInitialLocation());

[flackr, 2013/06/19 15:16:49]

Add comment that we use the start location to make sure that it is reparented to
the same display as it was initially on. There may be a clearer way of ensuring
this (i.e. just passing the root window's bounds)

[varkha, 2013/06/19 15:49:22]

Done.

+    wm::ConvertPointToScreen(GetTarget()->parent(), &start_location_in_screen);
+    gfx::Rect near_start_location(start_location_in_screen, gfx::Size());
+    GetTarget()->SetDefaultParentByRootWindow(GetTarget()->GetRootWindow(),
+                                              near_start_location);

[flackr, 2013/06/19 15:16:49]

nit: Construct gfx::Rect in place for the parameter since it's only used once.

[varkha, 2013/06/19 15:49:22]

No need with using the root coordinates.

   }
 }