extensions/markdown-language-features/src/commands/showPreviewSecuritySelector.ts/ShowPreviewSecuritySelectorCommand/execute
class ShowPreviewSecuritySelectorCommand:	public execute(resource: string | undefined) {
		if (this.previewManager.activePreviewResource) {
			this.previewSecuritySelector.showSecuritySelectorForResource(this.previewManager.activePreviewResource);
		} else if (resource) {
			const source = vscode.Uri.parse(resource);
			this.previewSecuritySelector.showSecuritySelectorForResource(source.query ? vscode.Uri.parse(source.query) : source);
		} else if (vscode.window.activeTextEditor && isMarkdownFile(vscode.window.activeTextEditor.document)) {
			this.previewSecuritySelector.showSecuritySelectorForResource(vscode.window.activeTextEditor.document.uri);
		}
	}