underline clips that are linked

app/node/block/block.cpp

@@ -273,3 +273,8 @@ const QVector<Block*> &Block::linked_clips()
   return linked_clips_;
 }
 
+bool Block::HasLinks()
+{
+  return !linked_clips_.isEmpty();
+}
+

app/node/block/block.h

@@ -76,6 +76,7 @@ public:
   static void Unlink(Block* a, Block* b);
   static bool AreLinked(Block* a, Block* b);
   const QVector<Block*>& linked_clips();
+  bool HasLinks();
 
 public slots:
   /**