Fix selection bug when overlaying objects

This is an unexpected behavior. If I use the template and add a cyclohexane, then select the lasso tool, the cyclohexane (or last item drawn) is automatically selected. If I add a cyclohexane, then use the template to add a benzene over the structure so they perfectly align, converting the cyclohexane to a benzene, then select the lasso tool nothing is selected. It is reproducible, but I am not sure how extensive (or troublesome) the issue is.