Index: src/app/qgssnappingdialog.cpp
===================================================================
--- src/app/qgssnappingdialog.cpp	(Revision 14696)
+++ src/app/qgssnappingdialog.cpp	(Arbeitskopie)
@@ -27,6 +27,7 @@
 #include <QComboBox>
 #include <QLineEdit>
 #include <QDockWidget>
+#include <QPushButton>
 
 
 class QgsSnappingDock : public QDockWidget
@@ -63,9 +64,9 @@
   else
   {
     connect( mButtonBox, SIGNAL( accepted() ), this, SLOT( apply() ) );
+    connect( mButtonBox->button(QDialogButtonBox::Apply), SIGNAL( clicked() ), this, SLOT( apply() ) );
   }
-  connect( QgsMapLayerRegistry::instance(), SIGNAL( layerWasAdded( QgsMapLayer * ) ), this, SLOT( update() ) );
-  connect( QgsMapLayerRegistry::instance(), SIGNAL( layerWillBeRemoved( QString ) ), this, SLOT( update() ) );
+  connect( QgsMapLayerRegistry::instance(), SIGNAL( layerWasAdded( QgsMapLayer * ) ), this, SLOT( connectUpdate( QgsMapLayer *) ) );
 
   update();
 
@@ -106,8 +107,8 @@
   QSettings myQsettings;
   bool myDockFlag = myQsettings.value( "/qgis/dockSnapping", false ).toBool();
 
-  double defaultSnapppingTolerance = myQsettings.value( "/qgis/digitizing/default_snapping_tolerance", 0 ).toDouble();
-  int defaultSnapppingUnit = myQsettings.value( "/qgis/digitizing/default_snapping_tolerance_unit", 0 ).toInt();
+  double defaultSnappingTolerance = myQsettings.value( "/qgis/digitizing/default_snapping_tolerance", 0 ).toDouble();
+  int defaultSnappingUnit = myQsettings.value( "/qgis/digitizing/default_snapping_tolerance_unit", 0 ).toInt();
   QString defaultSnappingString = myQsettings.value( "/qgis/digitizing/default_snap_mode", "to vertex" ).toString();
 
   int defaultSnappingStringIdx = 0;
@@ -133,9 +134,12 @@
 
   mLayerTreeWidget->clear();
 
-  for ( int i = 0; i < mMapCanvas->layerCount(); ++i )
+  QMap< QString, QgsMapLayer *> mapLayers = QgsMapLayerRegistry::instance()->mapLayers();
+  int a = mapLayers.count();
+  QMap< QString, QgsMapLayer *>::iterator it;
+  for ( it = mapLayers.begin(); it != mapLayers.end() ; ++it )
   {
-    QgsVectorLayer *currentVectorLayer = qobject_cast<QgsVectorLayer *>( mMapCanvas->layer( i ) );
+    QgsVectorLayer *currentVectorLayer = qobject_cast<QgsVectorLayer *>( it.value() );
     if ( !currentVectorLayer )
       continue;
 
@@ -160,7 +164,7 @@
     QLineEdit *leTolerance = new QLineEdit( mLayerTreeWidget );
     QDoubleValidator *validator = new QDoubleValidator( leTolerance );
     leTolerance->setValidator( validator );
-    leTolerance->setText( QString::number( defaultSnapppingTolerance, 'f' ) );
+    leTolerance->setText( QString::number( defaultSnappingTolerance, 'f' ) );
 
     mLayerTreeWidget->setItemWidget( item, 3, leTolerance );
 
@@ -168,7 +172,7 @@
     QComboBox *cbxUnits = new QComboBox( mLayerTreeWidget );
     cbxUnits->insertItem( 0, tr( "map units" ) );
     cbxUnits->insertItem( 1, tr( "pixels" ) );
-    cbxUnits->setCurrentIndex( defaultSnapppingUnit );
+    cbxUnits->setCurrentIndex( defaultSnappingUnit );
     mLayerTreeWidget->setItemWidget( item, 4, cbxUnits );
 
     int idx = layerIdList.indexOf( currentVectorLayer->getLayerID() );
@@ -262,3 +266,10 @@
   else
     QDialog::show();
 }
+
+
+void QgsSnappingDialog::connectUpdate(QgsMapLayer * theMapLayer)
+{
+  connect( theMapLayer,SIGNAL( destroyed() ),this,SLOT( update() ) );
+  update();
+}
Index: src/app/qgssnappingdialog.h
===================================================================
--- src/app/qgssnappingdialog.h	(Revision 14696)
+++ src/app/qgssnappingdialog.h	(Arbeitskopie)
@@ -18,6 +18,7 @@
 #ifndef QGSSNAPPINGDIALOG_H
 #define QGSSNAPPINGDIALOG_H
 
+#include "qgsmaplayer.h"
 #include "ui_qgssnappingdialogbase.h"
 
 class QDockWidget;
@@ -41,12 +42,12 @@
     //! apply the changes
     void apply();
 
-    //! update the Dialog
-    void update();
-
     //! show dialog or dock
     void show();
 
+    //! connect to the layers destroyed() and then update()
+    void connectUpdate(QgsMapLayer* theMapLayer);
+
   protected:
     /**Constructor
     @param canvas pointer to the map canvas (for detecting which vector layers are loaded
@@ -67,6 +68,10 @@
     QgsMapCanvas* mMapCanvas;
 
     QDockWidget *mDock;
+
+  private slots:
+    //! update the Dialog
+    void update();
 };
 
 #endif
Index: src/app/qgsprojectproperties.h
===================================================================
--- src/app/qgsprojectproperties.h	(Revision 14696)
+++ src/app/qgsprojectproperties.h	(Arbeitskopie)
@@ -21,7 +21,6 @@
 #include "ui_qgsprojectpropertiesbase.h"
 #include "qgis.h"
 #include "qgisgui.h"
-#include "qgssnappingdialog.h"
 #include "qgscontexthelp.h"
 
 class QgsMapCanvas;
Index: src/core/qgsmaplayerregistry.cpp
===================================================================
--- src/core/qgsmaplayerregistry.cpp	(Revision 14696)
+++ src/core/qgsmaplayerregistry.cpp	(Arbeitskopie)
@@ -111,6 +111,7 @@
   {
     emit layerWillBeRemoved( it.key() );
     delete it.value(); // delete the map layer
+    mMapLayers.remove( it.key() );
   }
   mMapLayers.clear();
 
Index: src/ui/qgssnappingdialogbase.ui
===================================================================
--- src/ui/qgssnappingdialogbase.ui	(Revision 14696)
+++ src/ui/qgssnappingdialogbase.ui	(Arbeitskopie)
@@ -30,7 +30,7 @@
      </property>
      <column>
       <property name="text">
-       <string> </string>
+       <string/>
       </property>
      </column>
      <column>
@@ -61,7 +61,7 @@
       <enum>Qt::Horizontal</enum>
      </property>
      <property name="standardButtons">
-      <set>QDialogButtonBox::Cancel|QDialogButtonBox::Ok</set>
+      <set>QDialogButtonBox::Apply|QDialogButtonBox::Cancel|QDialogButtonBox::Ok</set>
      </property>
     </widget>
    </item>