WYSIWYG Web Builder does not modify the code you manually insert. So if the code doesn't work then there is either a problem in the code or there is a conflict with other items on the page.I contacted PayPal support who checked the code and stated that it worked fine using thier publishing software and have said that it must be a problem with between WYSIWIG and IE9.
I think in this case there is a conflict with the transparent shape. Because you have used opacity for the shape, IE will disable click events for the combobox.