diff --git a/src/engine.ts b/src/engine.ts
index 8a04c65..98188c0 100644
--- a/src/engine.ts
+++ b/src/engine.ts
@@ -18,67 +18,6 @@
 // FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
 // DEALINGS IN THE SOFTWARE.
 
-class LayoutStorage {
-    private store: { [key: string]: ILayout[] };
-
-    constructor() {
-        this.store = {};
-    }
-
-    public getCurrentLayout(screen: number, activity: string, desktop: number): ILayout {
-        const key = this.keygen(screen, activity, desktop);
-
-        if (!this.store[key])
-            this.initEntry(key);
-
-        // TODO: if no layout, return floating layout, which is a static object.
-        return this.store[key][0];
-    }
-
-    public cycleLayout(screen: number, activity: string, desktop: number) {
-        const key = this.keygen(screen, activity, desktop);
-
-        const entry = this.store[key];
-        if (!entry) {
-            this.initEntry(key);
-            return;
-        }
-
-        for (;;) {
-            const layout = entry.shift();
-            if (!layout)
-                return;
-
-            entry.push(layout);
-
-            if (entry[0].isEnabled())
-                break;
-        }
-    }
-
-    private keygen(screen: number, activity: string, desktop: number): string {
-        let key = String(screen);
-
-        if (Config.layoutPerActivity)
-            key += "@" + activity;
-        if (Config.layoutPerDesktop)
-            key += "#" + desktop;
-
-        return key;
-    }
-
-    private initEntry(key: string) {
-        const entry = [];
-        // TODO: user config
-        entry.push(new TileLayout());
-        entry.push(new MonocleLayout());
-        entry.push(new SpreadLayout());
-        entry.push(new StairLayout());
-
-        this.store[key] = entry;
-    }
-}
-
 class TilingEngine {
     public jiggle: boolean;
 
diff --git a/src/layoutstorage.ts b/src/layoutstorage.ts
new file mode 100644
index 0000000..df14723
--- /dev/null
+++ b/src/layoutstorage.ts
@@ -0,0 +1,80 @@
+// Copyright (c) 2018 Eon S. Jeon <esjeon@hyunmu.am>
+//
+// Permission is hereby granted, free of charge, to any person obtaining a
+// copy of this software and associated documentation files (the "Software"),
+// to deal in the Software without restriction, including without limitation
+// the rights to use, copy, modify, merge, publish, distribute, sublicense,
+// and/or sell copies of the Software, and to permit persons to whom the
+// Software is furnished to do so, subject to the following conditions:
+//
+// The above copyright notice and this permission notice shall be included in
+// all copies or substantial portions of the Software.
+//
+// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
+// THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
+// FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
+// DEALINGS IN THE SOFTWARE.
+
+class LayoutStorage {
+    private store: { [key: string]: ILayout[] };
+
+    constructor() {
+        this.store = {};
+    }
+
+    public getCurrentLayout(screen: number, activity: string, desktop: number): ILayout {
+        const key = this.keygen(screen, activity, desktop);
+
+        if (!this.store[key])
+            this.initEntry(key);
+
+        // TODO: if no layout, return floating layout, which is a static object.
+        return this.store[key][0];
+    }
+
+    public cycleLayout(screen: number, activity: string, desktop: number) {
+        const key = this.keygen(screen, activity, desktop);
+
+        const entry = this.store[key];
+        if (!entry) {
+            this.initEntry(key);
+            return;
+        }
+
+        for (;;) {
+            const layout = entry.shift();
+            if (!layout)
+                return;
+
+            entry.push(layout);
+
+            if (entry[0].isEnabled())
+                break;
+        }
+    }
+
+    private keygen(screen: number, activity: string, desktop: number): string {
+        let key = String(screen);
+
+        if (Config.layoutPerActivity)
+            key += "@" + activity;
+        if (Config.layoutPerDesktop)
+            key += "#" + desktop;
+
+        return key;
+    }
+
+    private initEntry(key: string) {
+        const entry = [];
+        // TODO: user config
+        entry.push(new TileLayout());
+        entry.push(new MonocleLayout());
+        entry.push(new SpreadLayout());
+        entry.push(new StairLayout());
+
+        this.store[key] = entry;
+    }
+}