Allow that not all mouse events of a map tool must be implemented.

git-svn-id: http://svn.osgeo.org/qgis/trunk/qgis@5149 c8812cc2-4d05-0410-92ff-de0c093fc19c

Author: wonder

src/gui/qgsmaptool.h

@@ -35,13 +35,13 @@ class QgsMapTool
     virtual ~QgsMapTool();
 
     //! Mouse move event for overriding
-    virtual void canvasMoveEvent(QMouseEvent * e) = 0;
+    virtual void canvasMoveEvent(QMouseEvent * e) { }
 
     //! Mouse press event for overriding
-    virtual void canvasPressEvent(QMouseEvent * e) = 0;
+    virtual void canvasPressEvent(QMouseEvent * e) { }
 
     //! Mouse release event for overriding
-    virtual void canvasReleaseEvent(QMouseEvent * e) = 0;
+    virtual void canvasReleaseEvent(QMouseEvent * e) { }
 
     //! Called when rendering has finished
     virtual void renderComplete() {}