diff --git a/vlsisapd/src/configuration/src/Configuration.cpp b/vlsisapd/src/configuration/src/Configuration.cpp
index 9028899a..1c33b236 100644
--- a/vlsisapd/src/configuration/src/Configuration.cpp
+++ b/vlsisapd/src/configuration/src/Configuration.cpp
@@ -132,15 +132,21 @@ namespace {
     else if ( attrType == "enumerate"  ) type = Parameter::Enumerate;
 
     _parameter = _configuration->getParameter ( attrId );
-
     if ( _parameter == NULL ) {
-      _parameter = _configuration->addParameter ( attrId
+      _parameter = _configuration->addParameter ( attrId 
                                                 , type
                                                 , _getAttributeValue("value")
                                                 );
-
     } else {
-      _parameter->setString ( _getAttributeValue("value") );
+      _parameter->setString ( _getAttributeValue("value"), false );
+    }
+
+    if ( type == Parameter::Percentage ) {
+      istringstream s ( _getAttributeValue("value") );
+      double ratio;
+      s >> ratio;
+
+      _parameter->setPercentage ( ratio );
     }
 
     if (   (type == Parameter::Enumerate)
@@ -345,12 +351,26 @@ namespace Cfg {
   { return _layout.buildWidget(); }
 
 
-  Parameter* Configuration::getParameter ( const string& name ) const
+  Parameter* Configuration::getParameter ( const string& name, Parameter::Type type ) const
   {
     map<const string,Parameter*>::const_iterator iparameter = _parameters.find(name);
-    if ( iparameter != _parameters.end() ) return iparameter->second;
+    if ( iparameter == _parameters.end() ) return NULL;
 
-    return NULL;
+    if ( type != Parameter::Unknown ) {
+      Parameter::Type t1 = (*iparameter).second->getType();
+      Parameter::Type t2 = type;
+
+      if ( t1 > t2 ) swap ( t1, t2 );
+
+      if (         (t1 != t2)
+         and not ( (t1 == Parameter::Double) and (t2 == Parameter::Percentage) )
+         and not ( (t1 == Parameter::Int   ) and (t2 == Parameter::Enumerate ) ) )
+        cerr << "[ERROR] Accessing " << Parameter::typeToString((*iparameter).second->getType())
+             << " parameter <" << (*iparameter).second->getId()
+             << "> as " << Parameter::typeToString(type)<< " (type mismatch)." << endl;
+    }
+
+    return (*iparameter).second;
   }
 
 
diff --git a/vlsisapd/src/configuration/src/Parameter.cpp b/vlsisapd/src/configuration/src/Parameter.cpp
index 80c65f1e..eed82c7a 100644
--- a/vlsisapd/src/configuration/src/Parameter.cpp
+++ b/vlsisapd/src/configuration/src/Parameter.cpp
@@ -37,6 +37,7 @@ namespace Cfg {
   string  Parameter::typeToString  ( Parameter::Type type )
   {
     switch ( type ) {
+      case Unknown:    return "unknown";
       case String:     return "string";
       case Int:        return "int";
       case Double:     return "double";
@@ -63,7 +64,114 @@ namespace Cfg {
     if ( type == Percentage ) {
       setPercentage ( asDouble() );
     }
+
+  //cerr << "New " << typeToString(_type) << " parameter " << _id << " value:" << _value << endl;
   }
   
 
+  bool  Parameter::asBool () const
+  {
+    if ( _type != Bool )
+      cerr << "[ERROR] Accessing " << Parameter::typeToString(_type)
+           << " parameter <" << _id
+           << "> as " << Parameter::typeToString(Bool)<< " (type mismatch)." << endl;
+
+    std::istringstream s ( _value ); bool b; s >> std::boolalpha >> b; return b;
+  }
+
+
+  int  Parameter::asInt () const
+  {
+    if ( (_type != Int) and (_type != Enumerate) )
+      cerr << "[ERROR] Accessing " << Parameter::typeToString(_type)
+           << " parameter <" << _id
+           << "> as " << Parameter::typeToString(Int)<< " (type mismatch)." << endl;
+
+    std::istringstream s ( _value ); int i; s >> i; return i;
+  }
+
+
+  double  Parameter::asDouble () const
+  {
+    if ( (_type != Double) and (_type != Percentage) )
+      cerr << "[ERROR] Accessing " << Parameter::typeToString(_type)
+           << " parameter <" << _id
+           << "> as " << Parameter::typeToString(Double)<< " (type mismatch)." << endl;
+
+    std::istringstream s ( _value ); double d; s >> d; return d;
+  }
+
+
+  double  Parameter::asPercentage () const
+  {
+    if ( (_type != Double) and (_type != Percentage) )
+      cerr << "[ERROR] Accessing " << Parameter::typeToString(_type)
+           << " parameter <" << _id
+           << "> as " << Parameter::typeToString(Percentage)<< " (type mismatch)." << endl;
+
+    std::istringstream s ( _value ); double r; s >> r; return r*100.0;
+  }
+
+
+  void  Parameter::setString ( const std::string& s, bool check )
+  {
+    if ( check and (_type != String) )
+      cerr << "[ERROR] Parameter::setString(): Setting " << Parameter::typeToString(_type)
+           << " parameter <" << _id
+           << "> as " << Parameter::typeToString(String)<< " (type mismatch)." << endl;
+
+    _value = s;
+    _onValueChanged();
+  }
+
+
+  void  Parameter::setBool ( bool b )
+  {
+    if ( _type != Bool )
+      cerr << "[ERROR] Parameter::setBool(): Setting " << Parameter::typeToString(_type)
+           << " parameter <" << _id
+           << "> as " << Parameter::typeToString(Bool)<< " (type mismatch)." << endl;
+
+    std::ostringstream s; s << std::boolalpha << b; _value = s.str();
+
+    _onValueChanged();
+  }
+
+
+  void  Parameter::setInt ( int i )
+  {
+    if ( (_type != Int) and (_type != Enumerate)  )
+      cerr << "[ERROR] Parameter::setInt(): Setting " << Parameter::typeToString(_type)
+           << " parameter <" << _id
+           << "> as " << Parameter::typeToString(Int)<< " (type mismatch)." << endl;
+
+    std::ostringstream s; s << i; _value = s.str();
+    _onValueChanged();
+  } 
+
+
+  void  Parameter::setDouble ( double d )
+  {
+    if ( (_type != Double) and (_type != Percentage)  )
+      cerr << "[ERROR] Parameter::setDouble(): Setting " << Parameter::typeToString(_type)
+           << " parameter <" << _id
+           << "> as " << Parameter::typeToString(Double)<< " (type mismatch)." << endl;
+
+    std::ostringstream s; s << d; _value = s.str();
+    _onValueChanged();
+  } 
+
+
+  void  Parameter::setPercentage ( double d )
+  {
+    if ( (_type != Double) and (_type != Percentage)  )
+      cerr << "[ERROR] Parameter::setPercentage(): Setting " << Parameter::typeToString(_type)
+           << " parameter <" << _id
+           << "> as " << Parameter::typeToString(Double)<< " (type mismatch)." << endl;
+
+    std::ostringstream s; s << (d/100.0); _value = s.str();
+    _onValueChanged();
+  }
+
+
 }  // End of Cfg namespace.
diff --git a/vlsisapd/src/configuration/src/ParameterWidget.cpp b/vlsisapd/src/configuration/src/ParameterWidget.cpp
index c7e39a0f..3c6a56f8 100644
--- a/vlsisapd/src/configuration/src/ParameterWidget.cpp
+++ b/vlsisapd/src/configuration/src/ParameterWidget.cpp
@@ -23,6 +23,7 @@
 // x-----------------------------------------------------------------x
 
 
+#include  "boost/bind.hpp"
 #include  <QLabel>
 #include  <QSpinBox>
 #include  <QCheckBox>
@@ -161,6 +162,10 @@ namespace Cfg {
 
     string valueId = _parameter->getId() + ".edit";
     _valueWidget->setObjectName ( valueId.c_str() );
+
+  //Parameter::ParameterChangedCb_t cb = boost::bind(&ParameterWidget::updateValueCb,this);
+
+    _parameter->registerCb ( boost::bind(&ParameterWidget::updateValueCb,this,_1) );
   }
 
 
@@ -224,6 +229,67 @@ namespace Cfg {
   }
 
 
+  void  ParameterWidget::updateValueCb ( Parameter* p )
+  {
+    if ( _parameter->getType() == Parameter::String )
+      {
+        QLineEdit* lineEdit = qobject_cast<QLineEdit*>(_valueWidget);
+        if ( _parameter->asString() != lineEdit->displayText().toStdString() ) return;
+
+        lineEdit->setText ( _parameter->asString().c_str() );
+      }
+    else if ( _parameter->getType() == Parameter::Bool )
+      {
+        QCheckBox* checkBox = qobject_cast<QCheckBox*>(_valueWidget);
+        if ( _parameter->asBool() == checkBox->isChecked() ) return;
+
+        checkBox->setCheckState ( Qt::Checked );
+      }
+    else if ( _parameter->getType() == Parameter::Int )
+      {
+        if ( hasFlags(UseSpinBox) ) {
+          QSpinBox* spinBox = qobject_cast<QSpinBox*>(_valueWidget);
+          if ( spinBox->value() == _parameter->asInt() ) return;
+
+          spinBox->setValue ( _parameter->asInt() );
+        } else {
+          QLineEdit* lineEdit = qobject_cast<QLineEdit*>(_valueWidget);
+          if ( _parameter->asString() == lineEdit->displayText().toStdString() ) return;
+
+          lineEdit->setText ( _parameter->asString().c_str() );
+        }
+      }
+    else if ( _parameter->getType() == Parameter::Double )
+      {
+        bool       success;
+        QLineEdit* lineEdit = qobject_cast<QLineEdit*>(_valueWidget);
+        if ( _parameter->asDouble() == lineEdit->displayText().toFloat(&success) ) return;
+
+        lineEdit->setText ( _parameter->asString().c_str() );
+      }
+    else if ( _parameter->getType() == Parameter::Percentage )
+      {
+        bool       success;
+        QLineEdit* lineEdit = qobject_cast<QLineEdit*>(_valueWidget);
+        double     value    = lineEdit->displayText().toFloat ( &success );
+
+        if ( value == _parameter->asPercentage() ) return;
+        lineEdit->setText ( QString("%1").arg(_parameter->asPercentage()) );
+      }
+    else if ( _parameter->getType() == Parameter::Enumerate )
+      {
+        QComboBox* comboBox = qobject_cast<QComboBox*>(_valueWidget);
+        const vector<Parameter::EnumValue>& values = _parameter->getValues();
+
+        if ( values[comboBox->currentIndex()]._value == _parameter->asInt() ) return;
+        for ( size_t ivalue=0 ; ivalue<values.size() ; ++ivalue ) {
+          if ( values[ivalue]._value == _parameter->asInt() )
+            comboBox->setCurrentIndex ( ivalue );
+        }
+      }
+  }
+
+
   void  ParameterWidget::enableSlaves ( int state )
   {
     ConfigurationWidget* cw = rparent<ConfigurationWidget*> ( this );
diff --git a/vlsisapd/src/configuration/src/vlsisapd/configuration/Configuration.h b/vlsisapd/src/configuration/src/vlsisapd/configuration/Configuration.h
index 4ab9cafd..1a73b4d3 100644
--- a/vlsisapd/src/configuration/src/vlsisapd/configuration/Configuration.h
+++ b/vlsisapd/src/configuration/src/vlsisapd/configuration/Configuration.h
@@ -48,7 +48,8 @@ namespace Cfg {
                                       getParameters  () const;
       inline const LayoutDescription& getLayout      () const;
       inline LayoutDescription&       getLayout      ();
-             Parameter*               getParameter   ( const std::string& id ) const;
+             Parameter*               getParameter   ( const std::string& id
+                                                     , Parameter::Type    type=Parameter::Unknown ) const;
              Parameter*               addParameter   ( const std::string& id
                                                      , Parameter::Type    type
                                                      , const std::string& value );
@@ -75,71 +76,65 @@ namespace Cfg {
 
   inline Parameter* getParamString ( const std::string& id, const std::string& value="<undefined>" )
   {
-    Parameter* parameter = Configuration::get()->getParameter(id);
+    Parameter* parameter = Configuration::get()->getParameter(id,Parameter::String);
     if ( parameter == NULL ) {
       parameter = Configuration::get()->addParameter ( id, Parameter::String, value );
     }
-
     return parameter;
   }
 
 
   inline Parameter* getParamBool ( const std::string& id, bool value=false )
   {
-    Parameter* parameter = Configuration::get()->getParameter(id);
+    Parameter* parameter = Configuration::get()->getParameter(id,Parameter::Bool);
     if ( parameter == NULL ) {
       parameter = Configuration::get()->addParameter ( id, Parameter::Bool, "false" );
       parameter->setBool ( value );
     }
-
     return parameter;
   }
 
 
   inline Parameter* getParamInt ( const std::string& id, int value=0 )
   {
-    Parameter* parameter = Configuration::get()->getParameter(id);
+    Parameter* parameter = Configuration::get()->getParameter(id,Parameter::Int);
     if ( parameter == NULL ) {
       parameter = Configuration::get()->addParameter ( id, Parameter::Int, "0" );
       parameter->setInt ( value );
     }
-
     return parameter;
   }
 
 
   inline Parameter* getParamEnumerate ( const std::string& id, int value=0 )
   {
-    Parameter* parameter = Configuration::get()->getParameter(id);
+    Parameter* parameter = Configuration::get()->getParameter(id,Parameter::Enumerate);
     if ( parameter == NULL ) {
       parameter = Configuration::get()->addParameter ( id, Parameter::Enumerate, "0" );
       parameter->setInt ( value );
     }
-
     return parameter;
   }
 
 
   inline Parameter* getParamDouble ( const std::string& id, double value=0.0 )
   {
-    Parameter* parameter = Configuration::get()->getParameter(id);
+    Parameter* parameter = Configuration::get()->getParameter(id,Parameter::Double);
     if ( parameter == NULL ) {
       parameter = Configuration::get()->addParameter ( id, Parameter::Double, "0.0" );
       parameter->setDouble ( value );
     }
-
     return parameter;
   }
 
 
   inline Parameter* getParamPercentage ( const std::string& id, double value=91.0 )
   {
-    Parameter* parameter = Configuration::get()->getParameter(id);
+    Parameter* parameter = Configuration::get()->getParameter(id,Parameter::Percentage);
     if ( parameter == NULL ) {
       parameter = Configuration::get()->addParameter ( id, Parameter::Percentage, "0.91" );
       parameter->setPercentage ( value );
     }
-
     return parameter;
   }
 
diff --git a/vlsisapd/src/configuration/src/vlsisapd/configuration/Parameter.h b/vlsisapd/src/configuration/src/vlsisapd/configuration/Parameter.h
index 2d41feba..2d3a0363 100644
--- a/vlsisapd/src/configuration/src/vlsisapd/configuration/Parameter.h
+++ b/vlsisapd/src/configuration/src/vlsisapd/configuration/Parameter.h
@@ -30,6 +30,7 @@
 #include  <string>
 #include  <sstream>
 #include  <iostream>
+#include  <boost/function.hpp>
 
 
 namespace Cfg {
@@ -37,16 +38,18 @@ namespace Cfg {
 
   class Parameter {
     public:
-      enum Type  { String     = 1
-                 , Int        = 2
-                 , Double     = 3
-                 , Bool       = 4
-                 , Percentage = 5
-                 , Enumerate  = 6
+      enum Type  { Unknown    = 0
+                 , String     = 1
+                 , Bool       = 2
+                 , Int        = 3
+                 , Enumerate  = 4
+                 , Double     = 5
+                 , Percentage = 6
                  };
       enum Flags { HasMin     = 0x1
                  , HasMax     = 0x2
                  };
+      typedef boost::function< void(Parameter*) >  ParameterChangedCb_t;
     public:
       class EnumValue {
         public:
@@ -56,55 +59,59 @@ namespace Cfg {
           int          _value;
       };
     public:
-      static std::string        typeToString  ( Type );
-    public:
-                                Parameter     ( const std::string& id
-                                              , Type               type
-                                              , const std::string& value );
-      inline const std::string& getId         () const;
-      inline const Type         getType       () const;
-      inline const std::vector<EnumValue>&
-                                getValues     () const;
-      inline const std::vector<std::string>&
-                                getSlaves     () const;
-      inline int                getFlags      () const;
-      inline bool               hasFlags      ( int mask ) const;
-      inline int                getMinInt     () const;
-      inline int                getMaxInt     () const;
-      inline double             getMinDouble  () const;
-      inline double             getMaxDouble  () const;
-      inline bool               checkValue    ( int ) const;
-      inline bool               checkValue    ( double ) const;
-      inline const std::string& asString      () const;
-      inline bool               asBool        () const;
-      inline int                asInt         () const;
-      inline double             asDouble      () const;
-      inline double             asPercentage  () const;
-      inline void               addValue      ( const std::string&, int );
-      inline void               addSlave      ( const std::string& );
-      inline void               setString     ( const std::string& );
-      inline void               setFlags      ( int mask );
-      inline void               unsetFlags    ( int mask );
-      inline void               setInt        ( int );
-      inline void               setDouble     ( double );
-      inline void               setBool       ( bool );
-      inline void               setPercentage ( double );
-      inline void               setMin        ( int );
-      inline void               setMax        ( int );
-      inline void               setMin        ( double );
-      inline void               setMax        ( double );
+      static std::string        typeToString    ( Type );
+    public:                                     
+                                Parameter       ( const std::string& id
+                                                , Type               type
+                                                , const std::string& value );
+      inline const std::string& getId           () const;
+      inline const Type         getType         () const;
+      inline const std::vector<EnumValue>&      
+                                getValues       () const;
+      inline const std::vector<std::string>&    
+                                getSlaves       () const;
+      inline int                getFlags        () const;
+      inline bool               hasFlags        ( int mask ) const;
+      inline int                getMinInt       () const;
+      inline int                getMaxInt       () const;
+      inline double             getMinDouble    () const;
+      inline double             getMaxDouble    () const;
+      inline bool               checkValue      ( int ) const;
+      inline bool               checkValue      ( double ) const;
+      inline const std::string& asString        () const;
+             bool               asBool          () const;
+             int                asInt           () const;
+             double             asDouble        () const;
+             double             asPercentage    () const;
+      inline void               addValue        ( const std::string&, int );
+      inline void               addSlave        ( const std::string& );
+             void               setString       ( const std::string&, bool check=true );
+      inline void               setFlags        ( int mask );
+      inline void               unsetFlags      ( int mask );
+             void               setBool         ( bool );
+             void               setInt          ( int );
+             void               setDouble       ( double );
+             void               setPercentage   ( double );
+      inline void               setMin          ( int );
+      inline void               setMax          ( int );
+      inline void               setMin          ( double );
+      inline void               setMax          ( double );
+      inline void               registerCb      ( ParameterChangedCb_t );
+    private:
+      inline void               _onValueChanged ();
     private:
     // Attributes.
-      std::string               _id;
-      Type                      _type;
-      std::string               _value;
-      std::vector<EnumValue>    _values;
-      int                       _flags;
-      int                       _minInt;
-      int                       _maxInt;
-      double                    _minDouble;
-      double                    _maxDouble;
-      std::vector<std::string>  _slaves;
+      std::string                        _id;
+      Type                               _type;
+      std::string                        _value;
+      std::vector<EnumValue>             _values;
+      int                                _flags;
+      int                                _minInt;
+      int                                _maxInt;
+      double                             _minDouble;
+      double                             _maxDouble;
+      std::vector<std::string>           _slaves;
+      std::vector<ParameterChangedCb_t>  _callbacks;
   };
 
 
@@ -118,7 +125,6 @@ namespace Cfg {
   inline double                 Parameter::getMinDouble () const { return _minDouble; }
   inline double                 Parameter::getMaxDouble () const { return _maxDouble; }
   inline const std::string&     Parameter::asString     () const { return _value; }
-  inline void                   Parameter::setString    ( const std::string& s ) { _value = s; }
 
   inline bool  Parameter::checkValue ( int value ) const {
     bool ok = not (   ( (_flags&HasMin) and (value < _minInt) )
@@ -148,23 +154,6 @@ namespace Cfg {
     _values.push_back ( EnumValue(label,value) );
   }
 
-
-  inline bool  Parameter::asBool () const
-  { std::istringstream s ( _value ); bool b; s >> std::boolalpha >> b; return b; }
-
-  inline int  Parameter::asInt () const
-  { std::istringstream s ( _value ); int i; s >> i; return i; }
-
-  inline double  Parameter::asDouble () const
-  { std::istringstream s ( _value ); double d; s >> d; return d; }
-
-  inline double  Parameter::asPercentage () const
-  { std::istringstream s ( _value ); double r; s >> r; return r*100.0; }
-
-  inline void  Parameter::setInt        ( int i )      { std::ostringstream s; s << i; _value = s.str(); } 
-  inline void  Parameter::setDouble     ( double d )   { std::ostringstream s; s << d; _value = s.str(); } 
-  inline void  Parameter::setBool       ( bool b )     { std::ostringstream s; s << std::boolalpha << b; _value = s.str(); }
-  inline void  Parameter::setPercentage ( double d )   { std::ostringstream s; s << (d/100.0); _value = s.str(); }
   inline void  Parameter::setFlags      ( int mask )   { _flags |= mask; }
   inline void  Parameter::unsetFlags    ( int mask )   { _flags &= ~mask; }
   inline void  Parameter::setMin        ( int min )    { _minInt = min; setFlags(HasMin); }
@@ -179,6 +168,11 @@ namespace Cfg {
   inline Parameter::EnumValue::EnumValue ( const std::string& label, int value )
     : _label(label), _value(value) { }
 
+  inline void  Parameter::registerCb ( ParameterChangedCb_t cb ) { _callbacks.push_back(cb); }
+
+  inline void  Parameter::_onValueChanged ()
+  { for ( size_t icb=0 ; icb<_callbacks.size() ; ++icb ) _callbacks[icb]( this ); }
+
 
 }  // End of Cfg namespace.
 
diff --git a/vlsisapd/src/configuration/src/vlsisapd/configuration/ParameterWidget.h b/vlsisapd/src/configuration/src/vlsisapd/configuration/ParameterWidget.h
index 0a1ae878..3f2514bf 100644
--- a/vlsisapd/src/configuration/src/vlsisapd/configuration/ParameterWidget.h
+++ b/vlsisapd/src/configuration/src/vlsisapd/configuration/ParameterWidget.h
@@ -54,6 +54,7 @@ namespace Cfg {
       inline bool       hasFlags        ( int mask ) const;
       inline void       setFlags        ( int mask );
       inline void       unsetFlags      ( int mask );
+             void       updateValueCb   ( Parameter* );
     public slots:
              void       updateValue     ();
              void       enableSlaves    ( int );