diff --git a/source/app/DialogSubWindowSelector.cpp b/source/app/DialogSubWindowSelector.cpp
index 525e4bf..6db7a9a 100755
--- a/source/app/DialogSubWindowSelector.cpp
+++ b/source/app/DialogSubWindowSelector.cpp
@@ -30,14 +30,13 @@
 namespace plaYUVer
 {
 
-DialogSubWindowSelector::DialogSubWindowSelector( QWidget *parent, QMdiArea *mdiArea ) :
-        QDialog( parent )
+DialogSubWindowSelector::DialogSubWindowSelector( QWidget *parent, QMdiArea *mdiArea, Int numberWindowsSelected ) :
+        QDialog( parent ),
+        m_iNumberOfSelectedWindows( numberWindowsSelected ),
+        m_pcMainWindowMdiArea( mdiArea )
 {
   QFont titleFont, menusFont;
 
-  // Set variables
-  m_pcMainWindowMdiArea = mdiArea;
-
   titleFont.setPointSize( 14 );
   titleFont.setBold( true );
   titleFont.setWeight( 75 );
@@ -64,6 +63,7 @@ DialogSubWindowSelector::DialogSubWindowSelector( QWidget *parent, QMdiArea *mdi
 
   m_pushButtonAdd = new QPushButton( "Add", this );
   m_pushButtonRemove = new QPushButton( "Remove", this );
+  m_pushButtonRemove->setEnabled( false );
 
   // Selected Sub Window List
   m_listSelectedWindows = new QListWidget( this );
@@ -138,6 +138,11 @@ void DialogSubWindowSelector::addSubWindow()
     m_listSelectedWindows->insertItems( 0, m_pcSelectedWindowListNames );
     updateSubWindowList();
   }
+  if( m_pcSelectedWindowListNames.size() >= m_iNumberOfSelectedWindows )
+  {
+    m_pushButtonAdd->setEnabled( false );
+  }
+  m_pushButtonRemove->setEnabled( true );
 }
 
 void DialogSubWindowSelector::removeSubWindow()
@@ -158,6 +163,14 @@ void DialogSubWindowSelector::removeSubWindow()
     m_listSelectedWindows->insertItems( 0, m_pcSelectedWindowListNames );
     updateSubWindowList();
   }
+  if( m_pcSelectedWindowListNames.size() < m_iNumberOfSelectedWindows )
+  {
+    m_pushButtonAdd->setEnabled( true );
+  }
+  if( m_pcSelectedWindowListNames.size() == 0 )
+  {
+    m_pushButtonRemove->setEnabled( false );
+  }
 }
 
 }  // Namespace SCode
diff --git a/source/app/DialogSubWindowSelector.h b/source/app/DialogSubWindowSelector.h
index 3c112dd..b7af5a2 100755
--- a/source/app/DialogSubWindowSelector.h
+++ b/source/app/DialogSubWindowSelector.h
@@ -51,7 +51,7 @@ class DialogSubWindowSelector: public QDialog
 Q_OBJECT
 
 public:
-  DialogSubWindowSelector( QWidget *parent = 0, QMdiArea *mdiArea = 0 );
+  DialogSubWindowSelector( QWidget *parent = 0, QMdiArea *mdiArea = 0, Int numberWindowsSelected = -1 );
 
   Void setSubWindowList( QStringList cWindowListNames );
   QStringList getSelectedWindows()
@@ -59,6 +59,7 @@ public:
     return m_pcSelectedWindowListNames;
   }
 private:
+  Int m_iNumberOfSelectedWindows;
   QMdiArea* m_pcMainWindowMdiArea;
   QStringList m_pcWindowListNames;
   QStringList m_pcSelectedWindowListNames;