The app compiled with 5.12RC looks fine on Windows 10 but looks old-fashioned Win2k-like when running on Windows 7/8. Manifest with common controls does exist in the executable.

 Configure cmdline:

configure -opensource -developer-build -confirm-license -opengl desktop -mp -nomake tests -nomake examples -I \"%cd%\\$openssl_dir\\Release\\include\" -openssl-linked OPENSSL_LIBS_DEBUG=\"%cd%\\$openssl_dir
Debug
lib
ssleay32.lib %cd%\\$openssl_dir\\Debug\\lib\\libeay32.lib\" OPENSSL_LIBS_RELEASE=\"%cd%\\$openssl_dir
Release
lib
ssleay32.lib %cd%\\$openssl_dir\\Release\\lib\\libeay32.lib\"

Linguist app screenshots are attached.