diff --git a/resources/style/settings.scss b/resources/style/settings.scss
index c6908bd21..14b84cc29 100644
--- a/resources/style/settings.scss
+++ b/resources/style/settings.scss
@@ -85,3 +85,10 @@
   overflow: auto;
   padding: 0.5rem 2rem 0.5rem 1.25rem;
 }
+
+.info-icon {
+  &:hover {
+    cursor: help;
+    color: var(--text-color-strong);
+  }
+}
diff --git a/src/frontend/Overlay.tsx b/src/frontend/Overlay.tsx
index 1d7b6d1d4..a110b7a3d 100644
--- a/src/frontend/Overlay.tsx
+++ b/src/frontend/Overlay.tsx
@@ -3,12 +3,12 @@ import React from 'react';
 import { TooltipLayer } from 'widgets/popovers';
 import { useStore } from './contexts/StoreContext';
 
-const Overlay = observer(() => {
+const Overlay = observer(({ document = window.document }: { document?: Document }) => {
   const { uiStore } = useStore();
 
   return (
     <div className={uiStore.theme}>
-      <TooltipLayer />
+      <TooltipLayer document={document} />
     </div>
   );
 });
diff --git a/src/frontend/components/PopupWindow.tsx b/src/frontend/components/PopupWindow.tsx
index 31e39e93b..fac8b7548 100644
--- a/src/frontend/components/PopupWindow.tsx
+++ b/src/frontend/components/PopupWindow.tsx
@@ -1,5 +1,6 @@
 import React, { useState, useEffect } from 'react';
 import ReactDOM from 'react-dom';
+import Overlay from '../Overlay';
 
 const PLATFORM = process.platform;
 interface IPopupWindowProps {
@@ -45,7 +46,12 @@ const PopupWindow: React.FC<IPopupWindowProps> = (props) => {
   }, []);
 
   if (win) {
-    return ReactDOM.createPortal(props.children, containerEl);
+    return ReactDOM.createPortal(
+      <>
+        {props.children} <Overlay document={win.document} />
+      </>,
+      containerEl,
+    );
   }
   return null;
 };
diff --git a/src/frontend/containers/ContentView/GalleryItem.tsx b/src/frontend/containers/ContentView/GalleryItem.tsx
index 9547f48fc..5041c212b 100644
--- a/src/frontend/containers/ContentView/GalleryItem.tsx
+++ b/src/frontend/containers/ContentView/GalleryItem.tsx
@@ -105,7 +105,7 @@ export const Thumbnail = observer(({ file, mounted, forceNoThumbnail }: ItemProp
         // The thumbnailPath of an image is always set, but may not exist yet.
         // When the thumbnail is finished generating, the path will be changed to `${thumbnailPath}?v=1`.
         if (freshlyGenerated) {
-          await when(() => file.thumbnailPath.endsWith('?v=1'), { timeout: 5000 });
+          await when(() => file.thumbnailPath.endsWith('?v=1'), { timeout: 8000 });
           if (!getThumbnail(file).endsWith('?v=1')) {
             throw new Error('Thumbnail generation timeout.');
           }
diff --git a/src/frontend/containers/Settings/index.tsx b/src/frontend/containers/Settings/index.tsx
index 9e871f3ff..9f958c3c0 100644
--- a/src/frontend/containers/Settings/index.tsx
+++ b/src/frontend/containers/Settings/index.tsx
@@ -2,7 +2,7 @@ import { shell } from 'electron';
 import { runInAction } from 'mobx';
 import { observer } from 'mobx-react-lite';
 import SysPath from 'path';
-import React, { useCallback, useEffect, useState } from 'react';
+import React, { ReactNode, useCallback, useEffect, useState } from 'react';
 import {
   chromeExtensionUrl,
   getDefaultBackupDirectory,
@@ -337,6 +337,23 @@ const ImportExport = observer(() => {
   );
 });
 
+const imageFormatInts: Partial<Record<IMG_EXTENSIONS_TYPE, ReactNode>> = {
+  exr: (
+    <span
+      // TODO: Get TooltipLayer working in PopupWindow: tried a bunch of things but no bueno
+      title="Experimental: May slow down the application when enabled (disabled by default)"
+      className="info-icon"
+    >
+      {IconSet.WARNING}
+    </span>
+  ),
+  psd: (
+    <span title="Only a low-resolution thumbnail will be available" className="info-icon">
+      {IconSet.INFO}
+    </span>
+  ),
+};
+
 const ImageFormatPicker = observer(() => {
   const { locationStore, fileStore } = useStore();
 
@@ -389,6 +406,7 @@ const ImageFormatPicker = observer(() => {
                 checked={newEnabledFileExtensions.has(ext)}
                 onChange={() => toggleExtension(ext)}
               />
+              {imageFormatInts[ext] && <> {imageFormatInts[ext]}</>}
             </div>
           ))}
         </div>
diff --git a/src/frontend/stores/LocationStore.ts b/src/frontend/stores/LocationStore.ts
index d07a94b31..9560a20e6 100644
--- a/src/frontend/stores/LocationStore.ts
+++ b/src/frontend/stores/LocationStore.ts
@@ -52,7 +52,10 @@ class LocationStore {
       const prefs = JSON.parse(localStorage.getItem(PREFERENCES_STORAGE_KEY) || '') as Preferences;
       (prefs.extensions || IMG_EXTENSIONS).forEach((ext) => this.enabledFileExtensions.add(ext));
     } catch (e) {
+      // If no preferences found, use defaults
       IMG_EXTENSIONS.forEach((ext) => this.enabledFileExtensions.add(ext));
+      // By default, disable EXR for now (experimental)
+      this.enabledFileExtensions.delete('exr');
     }
 
     // Get dirs from backend
diff --git a/src/main.ts b/src/main.ts
index a634913c8..ad38b8348 100644
--- a/src/main.ts
+++ b/src/main.ts
@@ -461,16 +461,18 @@ if (isDev()) {
 }
 
 autoUpdater.on('error', (error) => {
+  // Don't show error messages on startup
+  if (!hasCheckedForUpdateOnStartup) {
+    hasCheckedForUpdateOnStartup = true;
+    console.error('Auto-update error', error);
+    return;
+  }
+
   let errorMsg: string = (error.stack || error).toString() || 'Reason unknown, try again later.';
 
   // In case of no network connection...
   if (errorMsg.includes('INTERNET_DISCONNECTED')) {
-    // no need to show an error dialog on startup
-    if (!hasCheckedForUpdateOnStartup) {
-      hasCheckedForUpdateOnStartup = true;
-      return;
-    }
-    // Otherwise this error occured during a manual update check from the user, show a friendlier message
+    // This error occured during a manual update check from the user, show a friendlier message
     errorMsg = 'There seems to be an issue with your internet connection.';
   }
   dialog.showErrorBox('Auto-update error: ', errorMsg);
diff --git a/widgets/popovers/Tooltip.tsx b/widgets/popovers/Tooltip.tsx
index 49b923da1..ac2b5ffc6 100644
--- a/widgets/popovers/Tooltip.tsx
+++ b/widgets/popovers/Tooltip.tsx
@@ -2,7 +2,7 @@ import { Placement, VirtualElement } from '@popperjs/core';
 import React, { useEffect, useRef, useState } from 'react';
 import { usePopper } from 'react-popper';
 
-export const TooltipLayer = () => {
+export const TooltipLayer = ({ document }: { document: Document }) => {
   const popoverElement = useRef<HTMLDivElement>(null);
   const virtualElement = useRef<VirtualElement | null>(null);
   const popperOptions = useRef({
@@ -116,7 +116,7 @@ export const TooltipLayer = () => {
       document.removeEventListener('blur', handleHide, true);
       document.removeEventListener('keydown', handleEscape, true);
     };
-  }, [forceUpdate]);
+  }, [document, forceUpdate]);
 
   return (
     <div