After starting a self-compiled Qt Creator 3.5.0 I just get a black main window, but as you can see the context menu seems to behave normally. Qt Creator 3.4.2 was working just fine with the same build environment. It also seems other Windows users observed that problem (e.g. http://blog.qt.io/blog/2015/08/20/qt-creator-3-5-0-released/#comment-1196599)

My Qt 5.5.5 was built with these flags:
configure.bat -prefix %CD%\qtbase -debug-and-release -developer-build -opensource -confirm-license -c+11 -opengl desktop -platform win32-g+ -icu -I D:/icu/dist/include -L D:/icu/dist/lib -openssl -I D:/openssl-1.0.2d/dist/include -L D:/openssl-1.0.2d/dist/lib -nomake examples -nomake tests -no-strip -sse2 -sse3 -ssse3 -sse4.1 -sse4.2 -avx -avx2 -no-dbus -no-audio-backend

Qt Creator was build with these flags:
qmake -r "QT_PRIVATE_HEADERS=$$QT_BUILD_TREE\include" qtcreator.pro CONFIG+=release