[Pharo-dev] pharo --headless in Windows makes a Window show anyway

When running (from a Zeroconf install): pharo --headless Pharo.image it looks like that the window is not opening ( or it is opening and closing so fast that I do not see it). Then I have an image with Seaside, Magritte, and other things. When doing the same, I do see the window of one second and then it closes. Is it normal to have that window opening? That's annoying for scripts as it doesn't look good. On OSX I do not have this behavior. What causes that on Windows? Phil