diff --git a/web/pdf_sidebar.js b/web/pdf_sidebar.js
index 5f3ab94310e05..b85a0372ad2b0 100644
--- a/web/pdf_sidebar.js
+++ b/web/pdf_sidebar.js
@@ -69,9 +69,7 @@ const UI_NOTIFICATION_CLASS = "pdfSidebarNotification";
 class PDFSidebar {
   #isRTL = false;
 
-  #mouseMoveBound = this.#mouseMove.bind(this);
-
-  #mouseUpBound = this.#mouseUp.bind(this);
+  #mouseAC = null;
 
   #outerContainerWidth = null;
 
@@ -325,11 +323,13 @@ class PDFSidebar {
   }
 
   #addEventListeners() {
+    const { eventBus, outerContainer } = this;
+
     this.sidebarContainer.addEventListener("transitionend", evt => {
       if (evt.target === this.sidebarContainer) {
-        this.outerContainer.classList.remove("sidebarMoving");
+        outerContainer.classList.remove("sidebarMoving");
         // Ensure that rendering is triggered after opening/closing the sidebar.
-        this.eventBus.dispatch("resize", { source: this });
+        eventBus.dispatch("resize", { source: this });
       }
     });
 
@@ -346,7 +346,7 @@ class PDFSidebar {
       this.switchView(SidebarView.OUTLINE);
     });
     this.outlineButton.addEventListener("dblclick", () => {
-      this.eventBus.dispatch("toggleoutlinetree", { source: this });
+      eventBus.dispatch("toggleoutlinetree", { source: this });
     });
 
     this.attachmentsButton.addEventListener("click", () => {
@@ -357,12 +357,12 @@ class PDFSidebar {
       this.switchView(SidebarView.LAYERS);
     });
     this.layersButton.addEventListener("dblclick", () => {
-      this.eventBus.dispatch("resetlayers", { source: this });
+      eventBus.dispatch("resetlayers", { source: this });
     });
 
     // Buttons for view-specific options.
     this._currentOutlineItemButton.addEventListener("click", () => {
-      this.eventBus.dispatch("currentoutlineitem", { source: this });
+      eventBus.dispatch("currentoutlineitem", { source: this });
     });
 
     // Disable/enable views.
@@ -378,7 +378,7 @@ class PDFSidebar {
       }
     };
 
-    this.eventBus._on("outlineloaded", evt => {
+    eventBus._on("outlineloaded", evt => {
       onTreeLoaded(evt.outlineCount, this.outlineButton, SidebarView.OUTLINE);
 
       evt.currentOutlineItemPromise.then(enabled => {
@@ -389,7 +389,7 @@ class PDFSidebar {
       });
     });
 
-    this.eventBus._on("attachmentsloaded", evt => {
+    eventBus._on("attachmentsloaded", evt => {
       onTreeLoaded(
         evt.attachmentsCount,
         this.attachmentsButton,
@@ -397,12 +397,12 @@ class PDFSidebar {
       );
     });
 
-    this.eventBus._on("layersloaded", evt => {
+    eventBus._on("layersloaded", evt => {
       onTreeLoaded(evt.layersCount, this.layersButton, SidebarView.LAYERS);
     });
 
     // Update the thumbnailViewer, if visible, when exiting presentation mode.
-    this.eventBus._on("presentationmodechanged", evt => {
+    eventBus._on("presentationmodechanged", evt => {
       if (
         evt.state === PresentationModeState.NORMAL &&
         this.visibleView === SidebarView.THUMBS
@@ -418,13 +418,17 @@ class PDFSidebar {
       }
       // Disable the `transition-duration` rules when sidebar resizing begins,
       // in order to improve responsiveness and to avoid visual glitches.
-      this.outerContainer.classList.add(SIDEBAR_RESIZING_CLASS);
+      outerContainer.classList.add(SIDEBAR_RESIZING_CLASS);
+
+      this.#mouseAC = new AbortController();
+      const opts = { signal: this.#mouseAC.signal };
 
-      window.addEventListener("mousemove", this.#mouseMoveBound);
-      window.addEventListener("mouseup", this.#mouseUpBound);
+      window.addEventListener("mousemove", this.#mouseMove.bind(this), opts);
+      window.addEventListener("mouseup", this.#mouseUp.bind(this), opts);
+      window.addEventListener("blur", this.#mouseUp.bind(this), opts);
     });
 
-    this.eventBus._on("resize", evt => {
+    eventBus._on("resize", evt => {
       // When the *entire* viewer is resized, such that it becomes narrower,
       // ensure that the sidebar doesn't end up being too wide.
       if (evt.source !== window) {
@@ -443,15 +447,15 @@ class PDFSidebar {
         this.#updateWidth(this.#width);
         return;
       }
-      this.outerContainer.classList.add(SIDEBAR_RESIZING_CLASS);
+      outerContainer.classList.add(SIDEBAR_RESIZING_CLASS);
       const updated = this.#updateWidth(this.#width);
 
       Promise.resolve().then(() => {
-        this.outerContainer.classList.remove(SIDEBAR_RESIZING_CLASS);
+        outerContainer.classList.remove(SIDEBAR_RESIZING_CLASS);
         // Trigger rendering if the sidebar width changed, to avoid
         // depending on the order in which 'resize' events are handled.
         if (updated) {
-          this.eventBus.dispatch("resize", { source: this });
+          eventBus.dispatch("resize", { source: this });
         }
       });
     });
@@ -502,8 +506,8 @@ class PDFSidebar {
     // ... and ensure that rendering will always be triggered.
     this.eventBus.dispatch("resize", { source: this });
 
-    window.removeEventListener("mousemove", this.#mouseMoveBound);
-    window.removeEventListener("mouseup", this.#mouseUpBound);
+    this.#mouseAC?.abort();
+    this.#mouseAC = null;
   }
 }