MeasureDistance

- Abort mode via ESCAPE added

BoxZoom, BoxSelection and BoxElementSelection
- Change the cursor to give the user feedback about active mode.
- Abort mode via ESCAPE

src/Gui/NavigationStyle.cpp

@@ -1305,6 +1305,16 @@ void NavigationStyle::startSelection(NavigationStyle::SelectionMode mode)
         mouseSelection->grabMouseModel(viewer);
 }
 
+void NavigationStyle::abortSelection()
+{
+    pcPolygon.clear();
+    if (mouseSelection) {
+        mouseSelection->releaseMouseModel(true);
+        delete mouseSelection;
+        mouseSelection = 0;
+    }
+}
+
 void NavigationStyle::stopSelection()
 {
     pcPolygon.clear();