After looking at property classes, the first use that I thought of was for providing unity for fonts in all of my form objects. Oracle was one step ahead of me, and created visual attributes. Visual attributes are similar to property classes but are invoked and used a little differently. To create a visual attribute, select the Visual Attributes branch in the object navigator, and click the Create button on the vertical toolbar (it looks like a green plus with a white square next to it). This will add a visual attribute to your form module. Now you can assign a bunch of values to the visual attributes. Each visual object on your form has the capability to inherit these visual attributes with the Visual Attribute Group property.
The advantage of using property classes is that they can span multiple modules. Visual attributes are restricted to only one module. This is easily overcome by creating a master property class that contains the properties found in the visual attributes. Then, inherit those properties for all visual attributes for each of the modules in your application.