Clear out old status message if we do something.

EduNetworkBuilder/NetworkBuilder.cs

@@ -728,6 +728,7 @@ namespace EduNetworkBuilder
 
         private void pbNetworkView_MouseUp(object sender, MouseEventArgs e)
         {
+            lblStatus.Text = "";
             //find where we were clicked
             Point CenteredLocation = myNetwork.clickedPosCentered(e.Location);
             Point ClickLocation = myNetwork.clickedPos(e.Location);