Improve UX for deprecated settings (#55977)

* New settings editor shows depracted settings (only) when modified

* Add localized depracation text to augment the existing (nonlocalized) message

* Make deprecation warning less wordy, given they are already localized

src/vs/workbench/parts/preferences/browser/settingsTree.ts

@@ -145,7 +145,8 @@ export class SettingsTreeModel {
 		if (tocEntry.children) {
 			element.children = tocEntry.children.map(child => this.createSettingsTreeGroupElement(child, element));
 		} else if (tocEntry.settings) {
-			element.children = tocEntry.settings.map(s => this.createSettingsTreeSettingElement(<ISetting>s, element));
+			element.children = tocEntry.settings.map(s => this.createSettingsTreeSettingElement(<ISetting>s, element))
+				.filter(el => el.setting.deprecationMessage ? el.isConfigured : true);
 		}
 
 		this._treeElementsById.set(element.id, element);
@@ -1413,7 +1414,8 @@ export class SearchResultModel {
 
 	updateChildren(): void {
 		this.children = this.getFlatSettings()
-			.map(s => createSettingsTreeSettingElement(s, this, this._viewState.settingsTarget, this._configurationService));
+			.map(s => createSettingsTreeSettingElement(s, this, this._viewState.settingsTarget, this._configurationService))
+			.filter(el => el.setting.deprecationMessage ? el.isConfigured : true);
 
 		if (this.newExtensionSearchResults) {
 			const newExtElement = new SettingsTreeNewExtensionsElement();

src/vs/workbench/services/preferences/common/preferences.ts

@@ -44,6 +44,7 @@ export interface ISetting {
 	descriptionRanges: IRange[];
 	overrides?: ISetting[];
 	overrideOf?: ISetting;
+	deprecationMessage?: string;
 
 	// TODO@roblou maybe need new type and new EditorModel for GUI editor instead of ISetting which is used for text settings editor
 	type?: string | string[];

src/vs/workbench/services/preferences/common/preferencesModels.ts

@@ -551,9 +551,15 @@ export class DefaultSettings extends Disposable {
 		let result: ISetting[] = [];
 		for (let key in settingsObject) {
 			const prop = settingsObject[key];
-			if (!prop.deprecationMessage && this.matchesScope(prop)) {
+			if (this.matchesScope(prop)) {
 				const value = prop.default;
 				const description = (prop.description || '').split('\n');
+				if (prop.deprecationMessage) {
+					description.push(
+						'',
+						prop.deprecationMessage,
+						nls.localize('deprecatedSetting.unstable', "This setting should not be used, and will be removed in a future release."));
+				}
 				const overrides = OVERRIDE_PROPERTY_PATTERN.test(key) ? this.parseOverrideSettings(prop.default) : [];
 				result.push({
 					key,
@@ -567,7 +573,8 @@ export class DefaultSettings extends Disposable {
 					type: prop.type,
 					enum: prop.enum,
 					enumDescriptions: prop.enumDescriptions,
-					tags: prop.tags
+					tags: prop.tags,
+					deprecationMessage: prop.deprecationMessage,
 				});
 			}
 		}