A customer is interested in having Ghostscript create halftoned CMYK with proper spot color / overprint, where the halftone depends on the object type. This has (so far) required correcting many tag issues, but also needs some additions to the "DeviceN" colors to support tags.
I have been working on this, but hadn't noticed that it was assigned (by default) to Michael.
and this isn't actually a bug, but an enhancement (adding a new device)
I have a method in development that provides for object type specific halftones. It works, but there are some reference counting issues I need to track down.
Commit 2e66582c527646015731cd0f4a0fb2e2d1559887 replaces the tiffsep1 device with one that supports spot colors and also provides for object type specific halftones. The object type specific halftone commit 032cb22e6d63 added this for the graphics state. Note that pages with transparency don't support object type specific halftones for this or any other halftoned devices since the page is rendered to contone buffers, then halftoned once the page is complete.