[gnome-contacts] Add generic has_child_focus tracking helper to FieldRow

[Alexander Larsson <alexl src gnome org>]

commit 6f38554599f4280e1ddaa52e231f459a737f5665
Author: Alexander Larsson <alexl redhat com>
Date:   Mon Dec 19 11:26:05 2011 +0100

    Add generic has_child_focus tracking helper to FieldRow

 src/contacts-contact-pane.vala |   29 +++++++++++++++++++++++++++++
 1 files changed, 29 insertions(+), 0 deletions(-)
---
diff --git a/src/contacts-contact-pane.vala b/src/contacts-contact-pane.vala
index 0c458f4..1a44e41 100644
--- a/src/contacts-contact-pane.vala
+++ b/src/contacts-contact-pane.vala
@@ -23,6 +23,7 @@ using Gee;
 public class Contacts.FieldRow : Contacts.Row {
   Clickable clickable;
   int start;
+  bool has_child_focus;
 
   public FieldRow(RowGroup group) {
     base (group);
@@ -133,6 +134,34 @@ public class Contacts.FieldRow : Contacts.Row {
     return true;
   }
 
+  public override void parent_set (Widget? old_parent) {
+    if (old_parent != null) {
+      var old_parent_container = (old_parent as Container);
+      old_parent_container.set_focus_child.disconnect (parent_set_focus_child);
+    }
+
+    var parent_container = (this.get_parent () as Container);
+    has_child_focus = parent_container != null && parent_container.get_focus_child () == this;
+    if (parent_container != null)
+      parent_container.set_focus_child.connect (parent_set_focus_child);
+  }
+
+  public virtual signal void lost_child_focus () {
+  }
+
+  public void parent_set_focus_child (Container container, Widget? widget) {
+    var old_has_child_focus = has_child_focus;
+    has_child_focus = widget == this;
+
+    if (old_has_child_focus && !has_child_focus) {
+	  Idle.add(() => {
+	      if (!has_child_focus)
+		lost_child_focus ();
+	      return false;
+	    });
+    }
+  }
+
   public void pack (Widget w) {
     this.attach (w, 1, start++);
   }