Fix for potential divide by zero error

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/branches/WX_2_4_BRANCH@18433 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

contrib/src/stc/ScintillaWX.cpp

@@ -573,6 +573,8 @@ void ScintillaWX::DoMouseWheel(int rotation, int delta,
         }
     }
     else { // otherwise just scroll the window
+        if ( !delta )
+            delta = 120;
         wheelRotation += rotation;
         lines = wheelRotation / delta;
         wheelRotation -= lines * delta;