http://bugs.winehq.org/show_bug.cgi?id=31203
--- Comment #14 from Kai Blaschke webmaster@thw-theorie.de 2012-08-30 08:17:08 CDT --- The patch partially solves the black box problem by alpha-blending the background, which should improve the visual quality and somewhat reduce the flickering, but the main problems remain:
- As mentioned, the window isn't updated if anything changes below it. I'm not sure whether this happens for color-keyed windows or not, but what I've seen in the past is that Wine doesn't regularly or even consistently checks for changes in any element behind a window. In a Wine desktop, this should be relatively simple (as Wine draws everything), but if you mix Wine and native OS windows, this could be tricky. In Windows you can even smoothly play videos behind such a layered window.
- Currently, you can't click through transparent areas in a window. Most modern graphical UI environments support non-rectangular window shapes, so I don't suspect this to be a big problem.
Some developers place layered windows on top of another window, making the central area transparent to let the UI show through. Currently, such an application would become unusable, as you would just see a big black area in the center. Even with the partial patch, you would see the actual UI, but couldn't interact with it.
In Windows 8, this whole problem will probably get worse, as Microsoft allows devs to make client windows - which is potentially anything inside another window - layered, too. From a developer perspective this is quite nice, as it allows you to create some really fancy UIs, but in Wine, such application would currently be unusable.