Improve reliance on selector caching

js/components/MainWindow/PlaylistToggleButton.js

@@ -8,14 +8,14 @@ import { toggleWindow } from "../../actionCreators";
 const PlaylistToggleButton = props => (
   <div
     id="playlist-button"
-    className={classnames({ selected: props.getWindowOpen("playlist") })}
+    className={classnames({ selected: props.selected })}
     onClick={props.handleClick}
     title="Toggle Playlist Editor"
   />
 );
 
 const mapStateToProps = state => ({
-  getWindowOpen: getWindowOpen(state),
+  selected: getWindowOpen(state)("playlist"),
 });
 
 const mapDispatchToProps = {

js/selectors.ts

@@ -461,6 +461,7 @@ export function getLlamaMode(state: AppState) {
   return state.display.llama;
 }
 
+// TODO: This is poorly memoized. It invalidates when a window moves.
 export const getWindowSizes = createSelector(
   getGenWindows,
   getDoubled,