diff --git a/js/actionCreators/windows.js b/js/actionCreators/windows.ts
similarity index 70%
rename from js/actionCreators/windows.js
rename to js/actionCreators/windows.ts
index f96a46bf..830e43c0 100644
--- a/js/actionCreators/windows.js
+++ b/js/actionCreators/windows.ts
@@ -15,8 +15,9 @@ import {
   SET_WINDOW_VISIBILITY
 } from "../actionTypes";
 
-import { getPositionDiff } from "../resizeUtils";
+import { getPositionDiff, SizeDiff } from "../resizeUtils";
 import { applyDiff } from "../snapUtils";
+import { Action, Dispatchable, WindowId, WindowPositions } from "../types";
 
 // Dispatch an action and, if needed rearrange the windows to preserve
 // the existing edge relationship.
@@ -24,7 +25,7 @@ import { applyDiff } from "../snapUtils";
 // Works by checking the edges before the action is dispatched. Then,
 // after disatching, calculating what position change would be required
 // to restore those relationships.
-function withWindowGraphIntegrity(action) {
+function withWindowGraphIntegrity(action: Action): Dispatchable {
   return (dispatch, getState) => {
     const state = getState();
     const graph = getWindowGraph(state);
@@ -33,7 +34,7 @@ function withWindowGraphIntegrity(action) {
     dispatch(action);
 
     const newSizes = getWindowSizes(getState());
-    const sizeDiff = {};
+    const sizeDiff: SizeDiff = {};
     for (const window of Object.keys(newSizes)) {
       const original = originalSizes[window];
       const current = newSizes[window];
@@ -54,51 +55,56 @@ function withWindowGraphIntegrity(action) {
   };
 }
 
-export function toggleDoubleSizeMode() {
+export function toggleDoubleSizeMode(): Dispatchable {
   return withWindowGraphIntegrity({ type: TOGGLE_DOUBLESIZE_MODE });
 }
 
-export function toggleEqualizerShadeMode() {
+export function toggleEqualizerShadeMode(): Dispatchable {
   return withWindowGraphIntegrity({
     type: TOGGLE_WINDOW_SHADE_MODE,
     windowId: "equalizer"
   });
 }
 
-export function toggleMainWindowShadeMode() {
+export function toggleMainWindowShadeMode(): Dispatchable {
   return withWindowGraphIntegrity({
     type: TOGGLE_WINDOW_SHADE_MODE,
     windowId: "main"
   });
 }
 
-export function togglePlaylistShadeMode() {
+export function togglePlaylistShadeMode(): Dispatchable {
   return withWindowGraphIntegrity({
     type: TOGGLE_WINDOW_SHADE_MODE,
     windowId: "playlist"
   });
 }
 
-export function closeWindow(windowId) {
+export function closeWindow(windowId: WindowId): Dispatchable {
   return { type: CLOSE_WINDOW, windowId };
 }
 
-export function hideWindow(windowId) {
+export function hideWindow(windowId: WindowId): Dispatchable {
   return { type: SET_WINDOW_VISIBILITY, windowId, hidden: true };
 }
 
-export function showWindow(windowId) {
+export function showWindow(windowId: WindowId): Dispatchable {
   return { type: SET_WINDOW_VISIBILITY, windowId, hidden: false };
 }
 
-export function setWindowSize(windowId, size) {
+export function setWindowSize(
+  windowId: WindowId,
+  size: [number, number]
+): Dispatchable {
   return { type: WINDOW_SIZE_CHANGED, windowId, size };
 }
 
-export function toggleWindow(windowId) {
+export function toggleWindow(windowId: WindowId): Dispatchable {
   return { type: TOGGLE_WINDOW, windowId };
 }
 
-export function updateWindowPositions(positions) {
+export function updateWindowPositions(
+  positions: WindowPositions
+): Dispatchable {
   return { type: UPDATE_WINDOW_POSITIONS, positions };
 }
diff --git a/js/resizeUtils.ts b/js/resizeUtils.ts
index c6b72820..29fee02e 100644
--- a/js/resizeUtils.ts
+++ b/js/resizeUtils.ts
@@ -14,10 +14,8 @@ interface PositionDiff {
   };
 }
 
-interface SizeDiff {
+export interface SizeDiff {
   [key: string]: {
-    x: number;
-    y: number;
     width: number;
     height: number;
   };