apply #2712 and #2716 with slight modification. Thanks to Charles Timko.

git-svn-id: http://svn.osgeo.org/qgis/trunk/qgis@13517 c8812cc2-4d05-0410-92ff-de0c093fc19c

Author: jef

python/gui/qgsmapcanvas.sip

@@ -170,6 +170,10 @@ class QgsMapCanvas : QGraphicsView
 
     //! Zoom out with fixed factor
     void zoomOut( );
+
+    //! Zoom to a specific scale
+    // added in 1.5
+    void zoomScale( double scale );
 
     //! Zoom with the factor supplied. Factor > 1 zooms in
     void zoomByFactor( double scaleFactor );

src/app/qgisapp.cpp

@@ -1220,6 +1220,12 @@ void QgisApp::showPythonDialog()
     mPythonUtils->getError( className, text );
     QMessageBox::critical( this, tr( "Error" ), tr( "Failed to open Python console:" ) + "\n" + className + ": " + text );
   }
+#ifdef Q_WS_MAC
+  else
+  {
+    addWindow( mActionShowPythonDialog );
+  }
+#endif
 }
 
 void QgisApp::createActionGroups()
@@ -4779,8 +4785,6 @@ void QgisApp::showScale( double theScale )
 
 void QgisApp::userScale()
 {
-  double currentScale = mMapCanvas->scale();
-
   QStringList parts = mScaleEdit->text().split( ':' );
   if ( parts.size() == 2 )
   {
@@ -4789,8 +4793,7 @@ void QgisApp::userScale()
     double rightSide = parts.at( 1 ).toDouble( &rightOk );
     if ( leftSide > 0.0 && leftOk && rightOk )
     {
-      double wantedScale = rightSide / leftSide;
-      mMapCanvas->zoomByFactor( wantedScale / currentScale );
+      mMapCanvas->zoomScale( rightSide / leftSide );
     }
   }
 }
@@ -4998,7 +5001,6 @@ void QgisApp::loadPythonSupport()
     mActionPluginSeparator2 = mPluginMenu->addSeparator();
     mPluginMenu->addAction( mActionShowPythonDialog );
     std::cout << "Python support ENABLED :-) " << std::endl; // OK
-
   }
 }
 
@@ -5255,7 +5257,7 @@ QgsVectorLayer* QgisApp::addVectorLayer( QString vectorLayerPath, QString baseNa
   else
   {
     QMessageBox::critical( this, tr( "Layer is not valid" ),
-                           tr( "The layer is not a valid layer and can not be added to the map" ) );
+                           tr( "The layer %1 is not a valid layer and can not be added to the map" ).arg( vectorLayerPath ) );
 
     delete layer;
     mMapCanvas->freeze( false );

src/gui/qgsmapcanvas.cpp

@@ -1057,6 +1057,11 @@ void QgsMapCanvas::zoomOut()
   zoomByFactor( mWheelZoomFactor );
 }
 
+void QgsMapCanvas::zoomScale( double newScale )
+{
+  zoomByFactor( newScale / scale() );
+}
+
 void QgsMapCanvas::zoomWithCenter( int x, int y, bool zoomIn )
 {
   if ( mDrawing )

src/gui/qgsmapcanvas.h

@@ -228,6 +228,10 @@ class GUI_EXPORT QgsMapCanvas : public QGraphicsView
     //! Zoom out with fixed factor
     void zoomOut( );
 
+    //! Zoom to a specific scale
+    // added in 1.5
+    void zoomScale( double scale );
+
     //! Zoom with the factor supplied. Factor > 1 zooms out, interval (0,1) zooms in
     void zoomByFactor( double scaleFactor );