ZooLib had always maintained the ZFakeWindow abstract interface between user interface elements and the hosting environment. This allowed ZooLib UI widgets to be used within MacApp applications, standalone applications, Control Panels, XCMD windows and XObject windows. It worked very well.

However, when the portability axis was across platforms rather than hosting environments there was the potential for a lot of replication and ugly code in ZWindow, the standalone application derivative of ZFakeWindow.

So, I abstracted the interface to OS-windows, placing it in ZOSWindow, and modified ZWindow to use a ZOSWindow, rather than be conditionally compiled for different platforms.