+class WXDLLEXPORT wxWindow;
+
+// ---------------------------------------------------------------------------
+// private constants
+// ---------------------------------------------------------------------------
+
+// Conversion
+static const double METRIC_CONVERSION_CONSTANT = 0.0393700787;
+
+// Scaling factors for various unit conversions
+static const double mm2inches = (METRIC_CONVERSION_CONSTANT);
+static const double inches2mm = (1/METRIC_CONVERSION_CONSTANT);
+
+static const double mm2twips = (METRIC_CONVERSION_CONSTANT*1440);
+static const double twips2mm = (1/(METRIC_CONVERSION_CONSTANT*1440));
+
+static const double mm2pt = (METRIC_CONVERSION_CONSTANT*72);
+static const double pt2mm = (1/(METRIC_CONVERSION_CONSTANT*72));