src/vs/workbench/common/editor/editorGroupModel.ts/EditorGroupModel/stick
class EditorGroupModel:	stick(candidate: EditorInput): EditorInput | undefined {
		const res = this.findEditor(candidate);
		if (!res) {
			return; // not found
		}

		const [editor, index] = res;

		this.doStick(editor, index);

		return editor;
	}