vtk 8.2.rc2 transparency rendering with mesa broken

I am trying to use vtk8.2.0 with our FEA application but I have problems rendering transparency.

I have written a test similar to TestQVTKOpenGLNativeWidget TestQVTKOpenGLNativeWidgetTransparent.cxx that should render transparent shapes. I cannot get them to show when using mesa 18.0.5 and opengl errors are reported err. The opaque shapes are properly displayed.

Using a non-Qt render window by commenting out the USE_QT_OPENGL define doesn't make a difference, and rendering on an Nvidia graphics card () does produce transparent shapes..