Popup's placement propery is wrong

[yanshouwang]

• .NET Core Version: 3.0, 3.1, 5.0
• Windows version: (winver) 20H2 (19042.985)
• Does the bug reproduce also in WPF for .NET Framework 4.8?: Yes

**Problem description: Popups in WPF show's in wrong place, when set to left the popup shows at right, set to right shows at left, set to up shows at top-right (which should shows at top-left) and set to bottom shows at bottom-right (which should shows at bottom-left).

Actual behavior:

Expected behavior:

Minimal repro:

[daisyTian0517]

@yanshouwang
I tested your code on my desktop, and the Popups are on right place. This should be because your device is in tablet mode. Soultion:
Please go to your Settings -> System -> Tablet , then choose Don't swtict to tablet mode for the When I use this device as a tablet.

[yanshouwang]

@daisyTian0517 No, my device is a PC, and the settings is alreay set to PC mode, I think this is related to the windows version or .NET sdk version. This issue doesn't occured on my workmates' computer which the windows and .net sdk version is lower then mine.

[daisyTian0517]

It may be not caused by SDK version or winVersion, my winVersion is 20H2, my wpf project target platform is .NET Framework 4.8. Do your workmates use the same machines as you?

[yanshouwang]

@daisyTian0517 yes, do you installed .net 5.0 SDK? I aslo install .NET 5.0 SDK

[yanshouwang]

@daisyTian0517 and this problem even affect my visual studio, but I tried some winform applications, which doesn't have this problem, so I think this only happened in WPF apps.

[daisyTian0517]

I also tested in .net core5 wpf app and didn't reproduce your issue. It's probably due to your device Settings, like a person who has simmilar issue with you.

[yanshouwang]

Maybe I should try to reinstall my windows to see if this still exists.

[MichaeIDietrich]

As far as I know the popup open direction depends on whether the PC is set to left handed or right handed. For a long time there was a link in the control panel called Tablet PC Settings for setting this option, but it was removed in some Windows 10 update for an unknown reason. You can still open the dialog by using the run dialog (Win + R) and entering shell:::{80F3F1D5-FECA-45F3-BC32-752C152E456E}. You can find the option in the second tab there.

By the way not all applications or frameworks honor this option.

[yanshouwang]

@MichaeIDietrich For me the right hand is set. I think this should be a LTR direction, but actually the popup shows with RTL