Zinc 3.0 allows you to use custom icons in your applications (Windows & Mac OSX Only).
Windows Projectors expect a valid .ICO File, whilst Mac OSX Projectors expect a valid .ICNS File. For more information on valid Icon Files, visit the link below:
Using Custom Icons in Zinc 3.0
This download includes sample .ICO and .ICNS Files which can be used to debug your own Icon Files if they are not working corretcly in your compiled Applications.