WPF Critical - AllowTransparency (windowless) bug

Question

I have a windowless application. AllowTransparency= true. In the application, with any control that uses a drop down component (i.e. ComboBox, Menu), the drop down stops working after changing the systems screen resolution. Example. I startup the application. All the menus and combo boxes work fine. I change my monitors resolution and when I run the app again the menus and combo boxes will no longer drop down when they are selected. If I reboot then all is fine. I've noticed that if I change AllowTransparency to false and I now longer have a windowless form then all is fine and I don't get this behaviour. I'm aware of KB article 937106 and I'm not sure if the hotfix would address what I'm seeing. Has anyone else seen this and if so... Is there a workaround other than not using AllowTransparency=true.

 

Thanks,

John P

Answer 1

Hello, does this happen on every machine? I can’t repro it… Anyway, if you only want a windowless window, not a transparent window, you don’t need to set AllowTransparency to true. Just set WindowStyle to None and ResizeMode to NoResize is enough.

 

Answer 2

Also, we fixed several issues with layered windows in 3.5.  You may want to download it and try it out.

Answer 3

Although this is an old post, I would like to mention that I have .NET 3.5 SP1 installed, Visual Studio 2008, and running Windows XP. I was easily able to reproduce this issue as I have encountered it as well.

I hate to say it, but the 3.5 SP1 did not solve this problem.

Anyone have news on this bug?

Answer 4

Another interesting note about this, I tested the same scenario on a co-worker's machine, and oddly enough his works fine. I'm starting to think it is related to a problem down at the video driver level. I'm running the latest ATI drivers while my coworker is using a Matrox card...

Answer 5

I am also seeing this problem, ATI Mobility Radeon 3400 HD with latest drivers, Win XP, .NET  3.5. Looks like a WPF bug to me, and a big one at that.

Answer 6

Yes, I take back what I said, I believe it's not a driver problem but rather a problem with WPF. Hope we get some feedback on this issue soon.

Answer 7

Bumping this message. We need to hear from the MSFT about this issue...

Answer 8

Hello,

i got a similar problem with transparent windows.

If "AllowsTransparency" is set to "true" for a WPF window without style maximizing will draw the window over the screen range. We counted 4 pixels over natrual screen border in all directions.

If "AllowsTransparency" is set to "false" the maximizing will be done correctly but it draw a border around the custom window style.

Is it posible to avoid this effect?