Regression: DDraw video output regressed for many applications by 0.4.9-dev-155-g9987f02 (extremely slow and black-flashing)

ros 0.4.9-dev-660-g30eb385 gcc dbg.
VBox 4.3.40, no Guest additions, VBEMP in use, inbuilt-Mesa.
AC97 drivers not installed.

In the past I could start Diablo II in fullscreen with the setup as described above.
This is not possible any longer.

Instead of displaying the main menu of the game, the graphics output will show a completely black and blank window. At best the menu flashes through for a fraction of a second and gets then totally black again.

While the menu is open, ros logs often: 0.4.9-dev-660-g30eb385_D2.log

fixme:(dll/directx/wine/ddraw/utils.c:584) Unhandled flags 0x20.

In 0.4.9-dev-0 the menu was always displayed.
And 0.4.8rls is also not yet affected

We should search for the guilty-rev.
I suspect it may have been introduced with WineSync3.3 (ddraw?).

I noticed the regression, when I wanted to commit the fix from CORE-13714 to master.
It's affected with and without that fix.