Hide the "Select pages" label, in the thumbnails sidebar, when split-merge is disabled

Currently there's a "pointless" label displayed, thus taking up vertical space, when `enableSplitMerge = false` is set.

Author: Snuffleupagus

web/app.js

@@ -461,6 +461,7 @@ const PDFViewerApplication = {
           foreground: AppOptions.get("pageColorsForeground"),
         }
       : null;
+    const enableSplitMerge = AppOptions.get("enableSplitMerge");
 
     let altTextManager;
     if (AppOptions.get("enableUpdatedAddImage")) {
@@ -602,7 +603,7 @@ const PDFViewerApplication = {
         pageColors,
         abortSignal,
         enableHWA,
-        enableSplitMerge: AppOptions.get("enableSplitMerge"),
+        enableSplitMerge,
         manageMenu: appConfig.viewsManager.manageMenu,
         addFileButton: appConfig.viewsManager.viewsManagerAddFileButton,
       });
@@ -764,6 +765,7 @@ const PDFViewerApplication = {
         elements: appConfig.viewsManager,
         eventBus,
         l10n,
+        enableSplitMerge,
       });
       this.viewsManager.onToggled = this.forceRendering.bind(this);
       this.viewsManager.onUpdateThumbnails = () => {

web/views_manager.js

@@ -98,6 +98,7 @@ class ViewsManager extends Sidebar {
     },
     eventBus,
     l10n,
+    enableSplitMerge = false,
   }) {
     super(
       {
@@ -142,6 +143,11 @@ class ViewsManager extends Sidebar {
 
     this.eventBus = eventBus;
 
+    if (!enableSplitMerge) {
+      viewsManagerStatus.hidden = true;
+    }
+    this._enableSplitMerge = enableSplitMerge;
+
     this.menu = new Menu(
       viewsManagerSelectorOptions,
       viewsManagerSelectorButton,
@@ -252,7 +258,9 @@ class ViewsManager extends Sidebar {
         return;
     }
 
-    this.viewsManagerStatus.hidden = view !== SidebarView.THUMBS;
+    if (this._enableSplitMerge) {
+      this.viewsManagerStatus.hidden = view !== SidebarView.THUMBS;
+    }
     this.viewsManagerAddFileButton.hidden = view !== SidebarView.THUMBS;
     this.viewsManagerCurrentOutlineButton.hidden = view !== SidebarView.OUTLINE;
     this.viewsManagerHeaderLabel.setAttribute(