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diff --git a/libs/cassowary/cassowary/ClDummyVariable.h b/libs/cassowary/cassowary/ClDummyVariable.h
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+// $Id$
+//
+// Cassowary Incremental Constraint Solver
+// Original Smalltalk Implementation by Alan Borning
+// This C++ Implementation by Greg J. Badros, <gjb@cs.washington.edu>
+// http://www.cs.washington.edu/homes/gjb
+// (C) 1998, 1999 Greg J. Badros and Alan Borning
+// See ../LICENSE for legal details regarding this software
+//
+// ClDummyVariable.h
+
+#ifndef ClDummyVariable_H
+#define ClDummyVariable_H
+
+#if defined(HAVE_CONFIG_H) && !defined(CONFIG_H_INCLUDED) && !defined(CONFIG_INLINE_H_INCLUDED)
+#include <cassowary/config-inline.h>
+#define CONFIG_INLINE_H_INCLUDED
+#endif
+
+#include "Cassowary.h"
+#include "ClAbstractVariable.h"
+
+class ClTableau;
+class ClSimplexSolver;
+
+class ClDummyVariable : public ClAbstractVariable {
+
+public:
+
+#ifdef CL_FIND_LEAK
+  ~ClDummyVariable() { --cDummyVariables; };
+
+  static long cDummyVariables;
+
+#endif
+
+protected:
+  friend class ClTableau;
+  friend class ClSimplexSolver;
+
+  ClDummyVariable(string Name = "") :
+    ClAbstractVariable(Name)
+    { 
+#ifdef CL_FIND_LEAK
+      ++cDummyVariables; 
+#endif
+    }
+
+  ClDummyVariable(long number, char *prefix) :
+    ClAbstractVariable(number,prefix)
+    { 
+#ifdef CL_FIND_LEAK
+      ++cDummyVariables; 
+#endif
+    }
+
+#ifndef CL_NO_IO
+  virtual ostream &PrintOn(ostream &xo) const
+  {  
+    xo << "[" << Name() << ":dummy]";
+    return xo;
+  }
+#endif
+
+  // Return true if this a dummy variable (used as a marker variable
+  // for required equality constraints).  Such variables aren't
+  // allowed to enter the basis when pivoting.
+  virtual bool IsDummy() const
+    { return true; }
+
+  // Return true if this a variable known outside the solver.  
+  // (We need to give such variables a Value after solving is complete.)
+  virtual bool IsExternal() const
+    { return false; }
+
+  // Return true if we can Pivot on this variable.
+  virtual bool IsPivotable() const
+    { return false; }
+
+  // Return true if this is a restricted (or slack) variable.  Such
+  // variables are constrained to be non-negative and occur only
+  // internally to the simplex solver.
+  virtual bool IsRestricted() const
+    { return true; }
+
+};
+
+#endif