Fix pr comments. Cleanup function. Simplify reaction

Signed-off-by: DmitriyNoa <dmytro.zharkov@gmail.com>

src/renderer/components/dock/dock-store/dock.store.ts

@@ -233,15 +233,6 @@ export class DockStore implements DockStorageState {
     }), reactionOpts);
   }
 
-  onTabsNumberChange(callback: (evt: DockTabsNumberEvent) => void) {
-    return reaction(() => this.tabsNumber, ((currentTabsNumber, previousTabsNumber) => {
-      callback({
-        currentTabsNumber,
-        previousTabsNumber,
-      });
-    }));
-  }
-
   hasTabs() {
     return this.tabs.length > 0;
   }

src/renderer/components/dock/dock-tabs.tsx

@@ -4,6 +4,7 @@
  */
 
 import React, { Fragment, useRef, useEffect, useState, UIEvent } from "react";
+import { reaction } from "mobx";
 import { Icon } from "../icon";
 import { Tabs } from "../tabs/tabs";
 import { DockTab } from "./dock-tab";
@@ -109,9 +110,12 @@ export const DockTabs = ({ tabs, autoFocus, selectedTab, onChangeTab, dockStore
     window.addEventListener("resize", onWindowResize);
 
     // update scroll state if tabs numbers has changed
-    dockStore.onTabsNumberChange(() => {
+    reaction(() => dockStore.tabsNumber, updateStateValues);
-      updateStateValues();
+
-    });
+    return () => {
+      window.removeEventListener("resize", onWindowResize);
+      elem.current.removeEventListener("scroll", updateScrollPosition);
+    };
   }, []);
 
   return (