productize the dialog style setting for desktop

src/vs/workbench/electron-sandbox/desktop.contribution.ts

@@ -268,6 +268,13 @@ import { IJSONSchema } from 'vs/base/common/jsonSchema';
 				'scope': ConfigurationScope.APPLICATION,
 				'description': nls.localize('titleBarStyle', "Adjust the appearance of the window title bar. On Linux and Windows, this setting also affects the application and context menu appearances. Changes require a full restart to apply.")
 			},
+			'window.dialogStyle': {
+				'type': 'string',
+				'enum': ['native', 'custom'],
+				'default': 'native',
+				'scope': ConfigurationScope.APPLICATION,
+				'description': nls.localize('dialogStyle', "Adjust the appearance of dialog windows.")
+			},
 			'window.nativeTabs': {
 				'type': 'boolean',
 				'default': false,

src/vs/workbench/services/dialogs/electron-sandbox/dialogService.ts

@@ -59,7 +59,7 @@ export class DialogService implements IDialogService {
 	}
 
 	private get useCustomDialog(): boolean {
-		return this.configurationService.getValue('workbench.dialogs.customEnabled') === true;
+		return this.configurationService.getValue('window.dialogStyle') === 'custom';
 	}
 
 	confirm(confirmation: IConfirmation): Promise<IConfirmationResult> {