Fix issue 14624: [PropertyGrid] FolderNameEditor does not use the modern FolderBrowserDialog

[SimonZhao888]

Fixes #14624

Proposed changes

• Before the FolderNameEditor used for folder paths in a PropertyGrid is the old folder browser, which is a system component control and called by FolderBrowserHelper
• Now use the modern FolderBrowserDialog to instead the old one, which is also a system component control and called by PInvokeCore.CoCreateInstance;
• Refactoring Unit Tests - FolderNameEditorTests.cs

Customer Impact

• [PropertyGrid] FolderNameEditor use the modern FolderBrowserDialog

Regression?

• No

Risk

• Mini

Screenshots

Before

14624-before.mp4

After

14624.mp4

Test methodology

• Manual testing

Test environment(s)

• 11.0.100-preview.5.26227.104

[Copilot]

Pull request overview

This PR updates the WinForms design-time FolderNameEditor used by PropertyGrid so it uses System.Windows.Forms.FolderBrowserDialog (which supports the modern/Vista-style folder picker when AutoUpgradeEnabled is enabled), and adjusts related design-time editors and tests accordingly.

Changes:

• Replaced the legacy FolderNameEditor.FolderBrowser usage with FolderBrowserDialog, and updated returned path handling to use SelectedPath.
• Updated SelectedPathEditor / InitialDirectoryEditor overrides to match the new InitializeDialog signature.
• Refactored/updated unit + UI integration tests and adjusted shipped public API text for the signature change.

Reviewed changes

Copilot reviewed 6 out of 6 changed files in this pull request and generated 2 comments.

Show a summary per file

File	Description
src/System.Windows.Forms.Design/src/System/Windows/Forms/Design/FolderNameEditor.cs	Switches the editor implementation to FolderBrowserDialog and updates InitializeDialog signature.
src/System.Windows.Forms.Design/src/System/Windows/Forms/Design/SelectedPathEditor.cs	Updates override to configure the new dialog type.
src/System.Windows.Forms.Design/src/System/Windows/Forms/Design/InitialDirectoryEditor.cs	Updates override to configure the new dialog type.
src/System.Windows.Forms.Design/src/PublicAPI.Shipped.txt	Updates the shipped API entry for FolderNameEditor.InitializeDialog.
src/System.Windows.Forms.Design/tests/UnitTests/System/Windows/Forms/Design/FolderNameEditorTests.cs	Refactors unit tests around the new dialog type/signature.
src/test/integration/UIIntegrationTests/FolderNameEditorTests.cs	Updates UI integration test to use FolderBrowserDialog / SelectedPath.

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[LeafShi1]

Thanks for the PR! I have a few concerns — see inline comments.

[SimonZhao888]

@KlausLoeffelmann we use the modern FolderBrowseDialog to replace the old Dialog, and as we cannot render a tabbed layout within the dialog's UI, and the descriptive information displayed on the old form is no longer applicable to the new one.
Older:

Modern Dialog:

I need to add a title to the dialog interface to indicate the corresponding attribute. Such as following:

and

Do you have any suggestions?

[KlausLoeffelmann]

Let's talk about that in the meeting.
I was under the impression, this is just a generic folder picker.
Maybe I need some help to understand the exact context better! 😸

[SimonZhao888]

FolderBrowserDialog prioritizes the modern Vista-style dialog; if that is not supported, WinForms automatically falls back to the legacy dialog. The code is as follows:

winforms/src/System.Windows.Forms/System/Windows/Forms/Dialogs/CommonDialogs/FolderBrowserDialog.cs

Lines 275 to 281 in 3b7f6e0

	protected override bool RunDialog(IntPtr hwndOwner) =>
	// If running the Vista dialog fails (e.g. on Server Core), we fall back to the
	// legacy dialog.
	UseVistaDialogInternal && TryRunDialogVista((HWND)hwndOwner, out bool returnValue)
	? returnValue
	: RunDialogOld((HWND)hwndOwner);

[KlausLoeffelmann]

I thought about that.
I think we should take it like that, and having the distinction in the title makes it sufficiently clear.

Just to be sure:
For the different TypeEditors, you are adjusting the respective Text ("Selected Path", "Initial Directory") in the dialog title, correct?

If that is the case, and with the fall-back to the classic folder dialog for headless system, let's take this!

Thanks!

[KlausLoeffelmann]

I saw the signature change only after I wrote the comment.
So...we're no longer compatible to the OOP Designer then is my stomach feeling - let's check this first.

[KlausLoeffelmann]

@LeafShi1, @SimonZhao888:
If we change the signature of that method here, are we then still compatible with projecting the editor into framework from the OOP Designer?

[SimonZhao888]

@KlausLoeffelmann, impact on designer projection risks:
Virtually none.
The reason is:

• The EditValue code here is not executed at design time,
• so it is unaffected by the signature change in InitializeDialog(...).
• Even if OOP Designer or framework projection mechanisms exist, they do not operate via this specific code.