Allow menus to stay open during a child view's drag and drop

ui/views/widget/widget.h

Index: ui/views/widget/widget.h
diff --git a/ui/views/widget/widget.h b/ui/views/widget/widget.h
index bc3f91473dd19de5175b0b939a69341424b7a329..1610faf8901dcc6b11ad52c7538ce4ab88f0f43c 100644
--- a/ui/views/widget/widget.h
+++ b/ui/views/widget/widget.h
@@ -793,6 +793,11 @@ class VIEWS_EXPORT Widget : public internal::NativeWidgetDelegate,
   // TODO(beng): remove once we fold those objects onto this one.
   void DestroyRootView();
 
+  bool child_drag_in_progress() const { return child_drag_in_progress_; }
+  void set_child_drag_in_progress(bool child_drag_in_progress) {
+    child_drag_in_progress_ = child_drag_in_progress;
+  }
+
  private:
   friend class ComboboxTest;
   friend class TextfieldTest;
@@ -858,6 +863,9 @@ class VIEWS_EXPORT Widget : public internal::NativeWidgetDelegate,
   // started from.
   View* dragged_view_;
 
+  // Whether or not a child of this widget is in the middle of a drag.
+  bool child_drag_in_progress_;

[Devlin, 2014/07/09 18:28:44]

This name isn't strictly true, since only the top-level widget will know about
this, but I think that's all that's needed (since it is the top-level widget
which closes the menu when it loses focus).  We could do this for each parent,
though, without much trouble.

+
   // See class documentation for Widget above for a note about ownership.
   InitParams::Ownership ownership_;