PNS: fixed crash on via dragging

pcbnew/router/pns_dragger.cpp

@@ -83,6 +83,9 @@ bool PNS_DRAGGER::startDragVia( const VECTOR2D& aP, PNS_VIA* aVia )
     VECTOR2I p0( aVia->Pos() );
     PNS_JOINT* jt = m_world->FindJoint( p0, aVia->Layers().Start(), aVia->Net() );
 
+    if( !jt )
+        return false;
+
     BOOST_FOREACH( PNS_ITEM* item, jt->LinkList() )
     {
         if( item->OfKind( PNS_ITEM::SEGMENT ) )

pcbnew/router/pns_tool_base.cpp

@@ -195,13 +195,19 @@ void PNS_TOOL_BASE::updateStartItem( TOOL_EVENT& aEvent )
 {
     int tl = getView()->GetTopLayer();
     VECTOR2I cp = m_ctls->GetCursorPosition();
+    VECTOR2I p;
+
     PNS_ITEM* startItem = NULL;
+    bool snapEnabled = true;
 
     if( aEvent.IsMotion() || aEvent.IsClick() )
     {
-        bool snapEnabled = !aEvent.Modifier( MD_SHIFT );
+        snapEnabled = !aEvent.Modifier( MD_SHIFT );
+        p = aEvent.Position();
+    } else {
+        p = cp;
+    }
 
-        VECTOR2I p( aEvent.Position() );
     startItem = pickSingleItem( p );
     m_router->EnableSnapping ( snapEnabled );
 
@@ -224,11 +230,6 @@ void PNS_TOOL_BASE::updateStartItem( TOOL_EVENT& aEvent )
             m_ctls->ForceCursorPosition( false );
         }
 
-//            if( startItem->Layers().IsMultilayer() )
-//                m_startLayer = tl;
-//            else
-//                m_startLayer = startItem->Layers().Start();
-
         m_startItem = startItem;
     }
     else
@@ -238,7 +239,6 @@ void PNS_TOOL_BASE::updateStartItem( TOOL_EVENT& aEvent )
         m_ctls->ForceCursorPosition( false );
     }
 }
-}
 
 
 void PNS_TOOL_BASE::updateEndItem( TOOL_EVENT& aEvent )

pcbnew/router/router_tool.cpp

@@ -660,7 +660,10 @@ int ROUTER_TOOL::mainLoop( PNS_ROUTER_MODE aMode )
                 performRouting();
         }
         else if( evt->IsAction( &ACT_Drag ) )
+        {
+            updateStartItem( *evt );
             performDragging();
+        }
 
         handleCommonEvents( *evt );
     }
@@ -731,6 +734,8 @@ void ROUTER_TOOL::performDragging()
         m_needsSync = true;
     }
 
+    m_startItem = NULL;
+
     ctls->SetAutoPan( false );
     ctls->ForceCursorPosition( false );
     highlightNet( false );