see PR pending https://git.janouch.name/p/sensei-raw-ctl/pulls/1.patch
bug 966747
fix gtk3_CFLAGS_OTHER using target_compile_options
the separator ';' is passed otherwise
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -45,8 +45,7 @@ if (BUILD_GUI)
 		DESTINATION ${CMAKE_INSTALL_DATADIR}/polkit-1/actions)
 
 	add_executable (${PROJECT_NAME}-gui ${PROJECT_NAME}-gui.c ${ui_out})
-	set_target_properties (${PROJECT_NAME}-gui PROPERTIES
-		COMPILE_FLAGS "${gtk3_CFLAGS_OTHER}")
+	target_compile_options(${PROJECT_NAME}-gui PRIVATE ${gtk3_CFLAGS_OTHER})
 	target_link_libraries (${PROJECT_NAME}-gui ${gtk3_LIBRARIES})
 	install (TARGETS ${PROJECT_NAME}-gui
 		DESTINATION ${CMAKE_INSTALL_BINDIR})