If I add ABI_X86_32 to gtk+, and then I re-emerge gtk+, it will notify in building: missing atk file. But if I manually add abi_x86_32 for dev-libs/atk, it will running well. I do not know how to change multilib at ebuild by right way, so I think I need some help at here.
Please show the actual error. dev-libs/atk is a deprecated package and atk pkg-config is provided by at-spi2-core for gtk+, which already depends on multilib versions of it when needed.