No custom changes, fresh checkouts.
I simply saw that NSResponderHotKeys is responsible for the errors seen by josh and myself, and that one is in CocoaUtils. I saw that LCLObjCBoolean is defined in CocoaPrivate, but I cannot add CocoaPrivate to the uses part of CocoaUtils, since CocoaPrivate already uses CocoaUtils.
0. I gave it a few more tries, and moved the LCLObjCBoolean definition to Cocoa_Extra. That avoids the circular reference, and allows to compile, with the following problems coming up:
1. In CocoaDatePicker, there's still TCocoaDatePicker.acceptsFirstResponder with the wrong type in interface and implementation.
2. In CocoaWSMenus, TCocoaMenuItem, you changed boolean to LCLObjCBoolean only in the interface, not the implementation.
3. In cocoaprinters_h.inc, TCocoaPrinterView, the update from boolean to LCLObjCBoolean was still missing for knowsPageRange and isFlipped.
With those changes, I was able to cross-compile to Darwin/Cocoa and the output works fine on High Sierra.