As far as a workaround, I see that you can add the Total Qty on Hand field to the main screen, but that appears to be it. And in this Forum thread (http://community.sagemas.com/t5/Personalization-Customization/Item-Quantity-Available-on-Main-Panel-of-Item-Inquiry-in-version/m-p/22923 ), Dawn posted a Script solution.
Other thoughts?