OpenFileDialog.ShowReadOnly does not work

[miloush]

• .NET Core Version: 7.0.0-preview.2.22152.2
• Windows version: 22581.1.amd64fre.ni_release.220318-1623
• Does the bug reproduce also in WPF for .NET Framework 4.8?: Yes

Problem description:

The OpenFileDialog ignores the ShowReadOnly property on the Vista code path.

Actual behavior:

No check box in the dialog.

Expected behavior:

A check box in the dialog as per documentation.

A dropdown option on the Open button would also be acceptable:

Minimal repro:

OpenFileDialog ofd = new OpenFileDialog();
ofd.ShowReadOnly = true;
ofd.ShowDialog();

[lindexi]

Sorry, what is the Vista code path ?

[miloush]

There are two code paths for the file dialogs, one uses GetOpenFileName API while the other one uses IFileDialog API (introduced in Windows Vista):

wpf/src/Microsoft.DotNet.Wpf/src/PresentationFramework/Microsoft/Win32/FileDialog.cs

Lines 823 to 827 in 3ccd6f5

	if (UseVistaDialog)
	{
	return RunVistaDialog(hwndOwner);
	}
	return RunLegacyDialog(hwndOwner);

The legacy one is used on Windows XP only. The Vista one is used everywhere else:

wpf/src/Microsoft.DotNet.Wpf/src/PresentationFramework/Microsoft/Win32/FileDialog.cs

Lines 1830 to 1833 in 3ccd6f5

	private bool UseVistaDialog
	{
	get { return Environment.OSVersion.Version.Major >= 6; }
	}

.NET Core never supported Windows XP, unlike .NET Framework. However, you can still get the legacy behavior with .NET Core using compatibility settings: