Add Mac system button area interfaces

Sine Striker

2023-12-17 52a662ed17db6c3a3ff2050d61bc2e06ea21b056

 src/widgets/CMakeLists.txt

@@ -14,6 +14,8 @@

if(WIN32)
    list(APPEND _src widgetwindowagent_win.cpp)
elseif(APPLE)
    list(APPEND _src widgetwindowagent_mac.cpp)
endif()

qwk_add_library(${PROJECT_NAME} AUTOGEN