diff --git a/toolkit/components/aboutthirdparty/AboutThirdParty.cpp b/toolkit/components/aboutthirdparty/AboutThirdParty.cpp
index 5794ec4e8936..0549cc268086 100644
--- a/toolkit/components/aboutthirdparty/AboutThirdParty.cpp
+++ b/toolkit/components/aboutthirdparty/AboutThirdParty.cpp
@@ -8,9 +8,311 @@
 
 #include "mozilla/ClearOnShutdown.h"
 #include "mozilla/dom/Promise.h"
+#include "mozilla/NativeNt.h"
 #include "mozilla/StaticPtr.h"
+#include "nsComponentManagerUtils.h"
+#include "nsIWindowsRegKey.h"
 #include "nsThreadUtils.h"
 
+#include <objbase.h>
+
+using namespace mozilla;
+
+namespace {
+
+// A callback function passed to EnumSubkeys uses this type
+// to control the enumeration loop.
+enum class CallbackResult { Continue, Stop };
+
+template <typename CallbackT>
+void EnumSubkeys(nsIWindowsRegKey* aRegBase, const CallbackT& aCallback) {
+  uint32_t count = 0;
+  if (NS_FAILED(aRegBase->GetChildCount(&count))) {
+    return;
+  }
+
+  for (uint32_t i = 0; i < count; ++i) {
+    nsAutoString subkeyName;
+    if (NS_FAILED(aRegBase->GetChildName(i, subkeyName))) {
+      continue;
+    }
+
+    nsCOMPtr<nsIWindowsRegKey> subkey;
+    if (NS_FAILED(aRegBase->OpenChild(subkeyName, nsIWindowsRegKey::ACCESS_READ,
+                                      getter_AddRefs(subkey)))) {
+      continue;
+    }
+
+    CallbackResult result = aCallback(subkeyName, subkey);
+    if (result == CallbackResult::Continue) {
+      continue;
+    } else if (result == CallbackResult::Stop) {
+      break;
+    } else {
+      MOZ_ASSERT_UNREACHABLE("Unexpected CallbackResult.");
+    }
+  }
+}
+
+}  // anonymous namespace
+
+class KnownModule final {
+  static KnownModule sKnownExtensions[static_cast<int>(KnownModuleType::Last)];
+
+  static bool GetInprocServerDllPathFromGuid(const GUID& aGuid,
+                                             nsAString& aResult) {
+    nsAutoStringN<60> subkey;
+    subkey.AppendPrintf(
+        "CLSID\\{%08x-%04x-%04x-%02x%02x-%02x%02x%02x%02x%02x%02x}\\"
+        "InProcServer32",
+        aGuid.Data1, aGuid.Data2, aGuid.Data3, aGuid.Data4[0], aGuid.Data4[1],
+        aGuid.Data4[2], aGuid.Data4[3], aGuid.Data4[4], aGuid.Data4[5],
+        aGuid.Data4[6], aGuid.Data4[7]);
+
+    nsresult rv;
+    nsCOMPtr<nsIWindowsRegKey> regKey =
+        do_CreateInstance("@mozilla.org/windows-registry-key;1", &rv);
+    if (NS_FAILED(rv)) {
+      return false;
+    }
+
+    rv = regKey->Open(nsIWindowsRegKey::ROOT_KEY_CLASSES_ROOT, subkey,
+                      nsIWindowsRegKey::ACCESS_READ);
+    if (NS_FAILED(rv)) {
+      return false;
+    }
+
+    rv = regKey->ReadStringValue(u""_ns, aResult);
+    return NS_SUCCEEDED(rv);
+  }
+
+  enum class HandlerType {
+    // For this type of handler, multiple extensions can be registered as
+    // subkeys under the handler subkey.
+    Multi,
+    // For this type of handler, a single extension can be registered as
+    // the default value of the handler subkey.
+    Single,
+  };
+
+  HandlerType mHandlerType;
+  nsLiteralString mSubkeyName;
+
+  using CallbackT = std::function<void(const nsString&, KnownModuleType)>;
+
+  void EnumInternal(nsIWindowsRegKey* aRegBase, KnownModuleType aType,
+                    const CallbackT& aCallback) const {
+    nsCOMPtr<nsIWindowsRegKey> shexType;
+    if (NS_FAILED(aRegBase->OpenChild(mSubkeyName,
+                                      nsIWindowsRegKey::ACCESS_READ,
+                                      getter_AddRefs(shexType)))) {
+      return;
+    }
+
+    switch (mHandlerType) {
+      case HandlerType::Single: {
+        nsAutoString valData;
+        GUID guid;
+        if (NS_FAILED(shexType->ReadStringValue(u""_ns, valData)) ||
+            FAILED(::CLSIDFromString(valData.get(), &guid))) {
+          return;
+        }
+
+        nsAutoString dllPath;
+        if (!GetInprocServerDllPathFromGuid(guid, dllPath)) {
+          return;
+        }
+
+        aCallback(dllPath, aType);
+        break;
+      }
+
+      case HandlerType::Multi:
+        EnumSubkeys(shexType, [aType, &aCallback](const nsString& aSubKeyName,
+                                                  nsIWindowsRegKey* aSubKey) {
+          GUID guid;
+          HRESULT hr = ::CLSIDFromString(aSubKeyName.get(), &guid);
+          if (hr == CO_E_CLASSSTRING) {
+            // If the key's name is not a GUID, the default value of the key
+            // may be a GUID.
+            nsAutoString valData;
+            if (NS_SUCCEEDED(aSubKey->ReadStringValue(u""_ns, valData))) {
+              hr = ::CLSIDFromString(valData.get(), &guid);
+            }
+          }
+
+          if (FAILED(hr)) {
+            return CallbackResult::Continue;
+          }
+
+          nsAutoString dllPath;
+          if (!GetInprocServerDllPathFromGuid(guid, dllPath)) {
+            return CallbackResult::Continue;
+          }
+
+          aCallback(dllPath, aType);
+          return CallbackResult::Continue;
+        });
+        break;
+
+      default:
+        MOZ_ASSERT_UNREACHABLE("Unexpected KnownModule::Type.");
+        break;
+    }
+  }
+
+  static void Enum(nsIWindowsRegKey* aRegBase, KnownModuleType aType,
+                   const CallbackT& aCallback) {
+    sKnownExtensions[static_cast<int>(aType)].EnumInternal(aRegBase, aType,
+                                                           aCallback);
+  }
+
+  KnownModule(HandlerType aHandlerType, nsLiteralString aSubkeyName)
+      : mHandlerType(aHandlerType), mSubkeyName(aSubkeyName) {}
+
+ public:
+  static void EnumAll(const CallbackT& aCallback) {
+    nsresult rv;
+    nsCOMPtr<nsIWindowsRegKey> regKey =
+        do_CreateInstance("@mozilla.org/windows-registry-key;1", &rv);
+    if (NS_FAILED(rv)) {
+      return;
+    }
+
+    // Icon Overlay Handlers are registered under HKLM only.
+    // No need to look at HKCU.
+    rv = regKey->Open(
+        nsIWindowsRegKey::ROOT_KEY_LOCAL_MACHINE,
+        u"Software\\Microsoft\\Windows\\CurrentVersion\\Explorer"_ns,
+        nsIWindowsRegKey::ACCESS_READ);
+    if (NS_SUCCEEDED(rv)) {
+      Enum(regKey, KnownModuleType::IconOverlay, aCallback);
+    }
+
+    // IMEs can be enumerated by
+    // ITfInputProcessorProfiles::EnumInputProcessorInfo, but enumerating
+    // the registry key is easier.
+    // The "HKLM\Software\Microsoft\CTF\TIP" subtree is shared between
+    // the 32-bits and 64 bits views.
+    // https://docs.microsoft.com/en-us/windows/win32/winprog64/shared-registry-keys
+    // This logic cannot detect legacy (TSF-unaware) IMEs.
+    rv = regKey->Open(nsIWindowsRegKey::ROOT_KEY_LOCAL_MACHINE,
+                      u"Software\\Microsoft\\CTF"_ns,
+                      nsIWindowsRegKey::ACCESS_READ);
+    if (NS_SUCCEEDED(rv)) {
+      Enum(regKey, KnownModuleType::Ime, aCallback);
+    }
+
+    // Because HKCR is a merged view of HKLM\Software\Classes and
+    // HKCU\Software\Classes, looking at HKCR covers both per-machine
+    // and per-user extensions.
+    rv = regKey->Open(nsIWindowsRegKey::ROOT_KEY_CLASSES_ROOT, u""_ns,
+                      nsIWindowsRegKey::ACCESS_READ);
+    if (NS_FAILED(rv)) {
+      return;
+    }
+
+    EnumSubkeys(regKey, [&aCallback](const nsString& aSubKeyName,
+                                     nsIWindowsRegKey* aSubKey) {
+      if (aSubKeyName.EqualsIgnoreCase("DesktopBackground") ||
+          aSubKeyName.EqualsIgnoreCase("AudioCD")) {
+        return CallbackResult::Continue;
+      }
+
+      if (aSubKeyName.EqualsIgnoreCase("Directory")) {
+        nsCOMPtr<nsIWindowsRegKey> regBackground;
+        if (NS_SUCCEEDED(aSubKey->OpenChild(u"Background\\shellex"_ns,
+                                            nsIWindowsRegKey::ACCESS_READ,
+                                            getter_AddRefs(regBackground)))) {
+          Enum(regBackground, KnownModuleType::ContextMenuHandler, aCallback);
+        }
+      } else if (aSubKeyName.EqualsIgnoreCase("Network")) {
+        nsCOMPtr<nsIWindowsRegKey> regNetworkTypes;
+        if (NS_SUCCEEDED(aSubKey->OpenChild(u"Type"_ns,
+                                            nsIWindowsRegKey::ACCESS_READ,
+                                            getter_AddRefs(regNetworkTypes)))) {
+          EnumSubkeys(
+              regNetworkTypes,
+              [&aCallback](const nsString&, nsIWindowsRegKey* aRegNetworkType) {
+                nsCOMPtr<nsIWindowsRegKey> regNetworkTypeShex;
+                if (NS_FAILED(aRegNetworkType->OpenChild(
+                        u"shellex"_ns, nsIWindowsRegKey::ACCESS_READ,
+                        getter_AddRefs(regNetworkTypeShex)))) {
+                  return CallbackResult::Continue;
+                }
+
+                Enum(regNetworkTypeShex, KnownModuleType::ContextMenuHandler,
+                     aCallback);
+                Enum(regNetworkTypeShex, KnownModuleType::PropertySheetHandler,
+                     aCallback);
+                return CallbackResult::Continue;
+              });
+        }
+      }
+
+      nsCOMPtr<nsIWindowsRegKey> regShex;
+      if (NS_FAILED(aSubKey->OpenChild(u"shellex"_ns,
+                                       nsIWindowsRegKey::ACCESS_READ,
+                                       getter_AddRefs(regShex)))) {
+        return CallbackResult::Continue;
+      }
+
+      Enum(regShex, KnownModuleType::ContextMenuHandler, aCallback);
+      Enum(regShex, KnownModuleType::PropertySheetHandler, aCallback);
+
+      if (aSubKeyName.EqualsIgnoreCase("AllFileSystemObjects") ||
+          aSubKeyName.EqualsIgnoreCase("Network") ||
+          aSubKeyName.EqualsIgnoreCase("NetShare") ||
+          aSubKeyName.EqualsIgnoreCase("NetServer") ||
+          aSubKeyName.EqualsIgnoreCase("DVD")) {
+        return CallbackResult::Continue;
+      }
+
+      if (aSubKeyName.EqualsIgnoreCase("Directory")) {
+        Enum(regShex, KnownModuleType::CopyHookHandler, aCallback);
+        Enum(regShex, KnownModuleType::DragDropHandler, aCallback);
+        return CallbackResult::Continue;
+      } else if (aSubKeyName.EqualsIgnoreCase("Drive")) {
+        Enum(regShex, KnownModuleType::DragDropHandler, aCallback);
+        return CallbackResult::Continue;
+      } else if (aSubKeyName.EqualsIgnoreCase("Folder")) {
+        Enum(regShex, KnownModuleType::DragDropHandler, aCallback);
+        return CallbackResult::Continue;
+      } else if (aSubKeyName.EqualsIgnoreCase("Printers")) {
+        Enum(regShex, KnownModuleType::CopyHookHandler, aCallback);
+        return CallbackResult::Continue;
+      }
+
+      Enum(regShex, KnownModuleType::DataHandler, aCallback);
+      Enum(regShex, KnownModuleType::DropHandler, aCallback);
+      Enum(regShex, KnownModuleType::IconHandler, aCallback);
+      Enum(regShex, KnownModuleType::PropertyHandler, aCallback);
+      Enum(regShex, KnownModuleType::InfotipHandler, aCallback);
+      return CallbackResult::Continue;
+    });
+  }
+
+  KnownModule() = delete;
+  KnownModule(KnownModule&&) = delete;
+  KnownModule& operator=(KnownModule&&) = delete;
+  KnownModule(const KnownModule&) = delete;
+  KnownModule& operator=(const KnownModule&) = delete;
+};
+
+KnownModule KnownModule::sKnownExtensions[] = {
+    {HandlerType::Multi, u"TIP"_ns},
+    {HandlerType::Multi, u"ShellIconOverlayIdentifiers"_ns},
+    {HandlerType::Multi, u"ContextMenuHandlers"_ns},
+    {HandlerType::Multi, u"CopyHookHandlers"_ns},
+    {HandlerType::Multi, u"DragDropHandlers"_ns},
+    {HandlerType::Multi, u"PropertySheetHandlers"_ns},
+    {HandlerType::Single, u"DataHandler"_ns},
+    {HandlerType::Single, u"DropHandler"_ns},
+    {HandlerType::Single, u"IconHandler"_ns},
+    {HandlerType::Single, u"{00021500-0000-0000-C000-000000000046}"_ns},
+    {HandlerType::Single, u"PropertyHandler"_ns},
+};
+
 namespace mozilla {
 
 static StaticRefPtr<AboutThirdParty> sSingleton;
@@ -30,13 +332,70 @@ already_AddRefed<AboutThirdParty> AboutThirdParty::GetSingleton() {
 AboutThirdParty::AboutThirdParty()
     : mPromise(new BackgroundThreadPromise::Private(__func__)) {}
 
+void AboutThirdParty::AddKnownModule(const nsString& aPath,
+                                     KnownModuleType aType) {
+  MOZ_ASSERT(!NS_IsMainThread());
+
+  const uint32_t flag = 1u << static_cast<uint32_t>(aType);
+  mKnownModules.WithEntryHandle(nt::GetLeafName(aPath), [flag](auto&& addPtr) {
+    if (addPtr) {
+      addPtr.Data() |= flag;
+    } else {
+      addPtr.Insert(flag);
+    }
+  });
+}
+
 void AboutThirdParty::BackgroundThread() {
   MOZ_ASSERT(!NS_IsMainThread());
   MOZ_ASSERT(mWorkerState == WorkerState::Running);
 
+  KnownModule::EnumAll(
+      [self = RefPtr{this}](const nsString& aDllPath, KnownModuleType aType) {
+        self->AddKnownModule(aDllPath, aType);
+      });
+
   mWorkerState = WorkerState::Done;
 }
 
+NS_IMETHODIMP AboutThirdParty::LookupModuleType(const nsAString& aLeafName,
+                                                uint32_t* aResult) {
+  constexpr uint32_t kShellExtensions =
+      1u << static_cast<uint32_t>(KnownModuleType::IconOverlay) |
+      1u << static_cast<uint32_t>(KnownModuleType::ContextMenuHandler) |
+      1u << static_cast<uint32_t>(KnownModuleType::CopyHookHandler) |
+      1u << static_cast<uint32_t>(KnownModuleType::DragDropHandler) |
+      1u << static_cast<uint32_t>(KnownModuleType::PropertySheetHandler) |
+      1u << static_cast<uint32_t>(KnownModuleType::DataHandler) |
+      1u << static_cast<uint32_t>(KnownModuleType::DropHandler) |
+      1u << static_cast<uint32_t>(KnownModuleType::IconHandler) |
+      1u << static_cast<uint32_t>(KnownModuleType::InfotipHandler) |
+      1u << static_cast<uint32_t>(KnownModuleType::PropertyHandler);
+
+  MOZ_ASSERT(NS_IsMainThread());
+
+  *aResult = 0;
+  if (mWorkerState != WorkerState::Done) {
+    return NS_OK;
+  }
+
+  uint32_t flags;
+  if (!mKnownModules.Get(aLeafName, &flags)) {
+    *aResult = nsIAboutThirdParty::ModuleType_Unknown;
+    return NS_OK;
+  }
+
+  if (flags & (1u << static_cast<uint32_t>(KnownModuleType::Ime))) {
+    *aResult |= nsIAboutThirdParty::ModuleType_IME;
+  }
+
+  if (flags & kShellExtensions) {
+    *aResult |= nsIAboutThirdParty::ModuleType_ShellExtension;
+  }
+
+  return NS_OK;
+}
+
 RefPtr<BackgroundThreadPromise> AboutThirdParty::CollectSystemInfoAsync() {
   MOZ_ASSERT(NS_IsMainThread());
 
diff --git a/toolkit/components/aboutthirdparty/AboutThirdParty.h b/toolkit/components/aboutthirdparty/AboutThirdParty.h
index 81f052fbe69d..b55ea4e75c5f 100644
--- a/toolkit/components/aboutthirdparty/AboutThirdParty.h
+++ b/toolkit/components/aboutthirdparty/AboutThirdParty.h
@@ -9,9 +9,26 @@
 
 #include "mozilla/MozPromise.h"
 #include "nsIAboutThirdParty.h"
+#include "nsTHashMap.h"
 
 namespace mozilla {
 
+enum class KnownModuleType : uint32_t {
+  Ime = 0,
+  IconOverlay,
+  ContextMenuHandler,
+  CopyHookHandler,
+  DragDropHandler,
+  PropertySheetHandler,
+  DataHandler,
+  DropHandler,
+  IconHandler,
+  InfotipHandler,
+  PropertyHandler,
+
+  Last,
+};
+
 using BackgroundThreadPromise =
     MozPromise<bool /* aIgnored */, nsresult, /* IsExclusive */ false>;
 
@@ -24,9 +41,11 @@ class AboutThirdParty final : public nsIAboutThirdParty {
   };
   Atomic<WorkerState, SequentiallyConsistent> mWorkerState;
   RefPtr<BackgroundThreadPromise::Private> mPromise;
+  nsTHashMap<nsStringCaseInsensitiveHashKey, uint32_t> mKnownModules;
 
   ~AboutThirdParty() = default;
   void BackgroundThread();
+  void AddKnownModule(const nsString& aPath, KnownModuleType aType);
 
  public:
   static already_AddRefed<AboutThirdParty> GetSingleton();
diff --git a/toolkit/components/aboutthirdparty/content/aboutThirdParty.css b/toolkit/components/aboutthirdparty/content/aboutThirdParty.css
index 046a89da1359..fb4ffb209cf5 100644
--- a/toolkit/components/aboutthirdparty/content/aboutThirdParty.css
+++ b/toolkit/components/aboutthirdparty/content/aboutThirdParty.css
@@ -39,6 +39,10 @@ h1 {
   margin: 0;
 }
 
+.module-tags {
+  margin-inline: .5em;
+}
+
 .module-tag {
   font-size: 12px;
   white-space: nowrap;
diff --git a/toolkit/components/aboutthirdparty/content/aboutThirdParty.html b/toolkit/components/aboutthirdparty/content/aboutThirdParty.html
index b8e0fd487d1b..dfca2c5c6b78 100644
--- a/toolkit/components/aboutthirdparty/content/aboutThirdParty.html
+++ b/toolkit/components/aboutthirdparty/content/aboutThirdParty.html
@@ -22,6 +22,8 @@
     <div>
       <button id="button-copy-to-clipboard"
               data-l10n-id="third-party-button-copy-to-clipboard"/>
+      <button id="button-reload" hidden
+              data-l10n-id="third-party-button-reload"/>
     </div>
 
     <h2 data-l10n-id="third-party-section-title"></h2>
@@ -52,6 +54,12 @@
           <img src="chrome://global/skin/icons/security-broken.svg"
                class="svg-common image-unsigned" hidden
                data-l10n-id="third-party-unsigned-icon"/>
+          <div class="module-tags">
+            <span class="module-tag tag-ime" hidden
+                  data-l10n-id="third-party-tag-ime"></span>
+            <span class="module-tag tag-shellex" hidden
+                  data-l10n-id="third-party-tag-shellex"></span>
+          </div>
           <button class="svg-button button-open-dir"
                   data-l10n-id="third-party-button-open">
             <img src="chrome://global/skin/icons/folder.svg"
diff --git a/toolkit/components/aboutthirdparty/content/aboutThirdParty.js b/toolkit/components/aboutthirdparty/content/aboutThirdParty.js
index 4322f49d0690..3a6289a7ccc9 100644
--- a/toolkit/components/aboutthirdparty/content/aboutThirdParty.js
+++ b/toolkit/components/aboutthirdparty/content/aboutThirdParty.js
@@ -55,6 +55,9 @@ async function fetchData() {
   for (const module of data.modules) {
     module.events = [];
     module.loadingOnMain = { count: 0, sum: 0 };
+    module.typeFlags = AboutThirdParty.lookupModuleType(
+      module.dllFile?.leafName
+    );
   }
 
   for (const [proc, perProc] of Object.entries(data.processes)) {
@@ -81,6 +84,14 @@ async function fetchData() {
     module.events.sort((a, b) => a.process.localeCompare(b.process));
   }
 
+  data.modules.sort((a, b) => {
+    // First sort by |typeFlags| in ascending order to move up
+    // unknown-type modules first, then sort by |loadingOnMain|
+    // in descending order to move up slower modules.
+    const diff = a.typeFlags - b.typeFlags;
+    return diff == 0 ? b.loadingOnMain - a.loadingOnMain : diff;
+  });
+
   return data.modules;
 }
 
@@ -144,6 +155,11 @@ function copyDataToClipboard(aData) {
       fileVersion: module.fileVersion,
     };
 
+    // We include the typeFlags field only when it's not 0 because
+    // typeFlags == 0 means system info is not yet collected.
+    if (module.typeFlags) {
+      copied.typeFlags = module.typeFlags;
+    }
     if (module.signedBy) {
       copied.signedBy = module.signedBy;
     }
@@ -191,6 +207,14 @@ function visualizeData(aData) {
       .querySelector(".button-expand")
       .addEventListener("click", onClickExpand);
 
+    const modTagsContainer = newCard.querySelector(".module-tags");
+    if (module.typeFlags & Ci.nsIAboutThirdParty.ModuleType_IME) {
+      modTagsContainer.querySelector(".tag-ime").hidden = false;
+    }
+    if (module.typeFlags & Ci.nsIAboutThirdParty.ModuleType_ShellExtension) {
+      modTagsContainer.querySelector(".tag-shellex").hidden = false;
+    }
+
     const btnOpenDir = newCard.querySelector(".button-open-dir");
     btnOpenDir.fileObj = module.dllFile;
     btnOpenDir.addEventListener("click", onClickOpenDir);
@@ -265,8 +289,27 @@ async function onLoad() {
       e.target.disabled = false;
     });
 
+  let hasData = false;
+  AboutThirdParty.collectSystemInfo()
+    .then(() => {
+      if (!hasData) {
+        // If collectSystemInfo was completed before fetchData,
+        // or there was no data available, visualizeData shows
+        // full info and the reload button is not needed.
+        return;
+      }
+
+      const button = document.getElementById("button-reload");
+      button.addEventListener("click", () => {
+        location.reload();
+      });
+      button.hidden = false;
+    })
+    .catch(Cu.reportError);
+
   const data = await fetchData();
-  if (!data?.length) {
+  hasData = data?.length;
+  if (!hasData) {
     document.getElementById("no-data").hidden = false;
     return;
   }
diff --git a/toolkit/components/aboutthirdparty/nsIAboutThirdParty.idl b/toolkit/components/aboutthirdparty/nsIAboutThirdParty.idl
index b4c2dcfd5167..b5cd55443d36 100644
--- a/toolkit/components/aboutthirdparty/nsIAboutThirdParty.idl
+++ b/toolkit/components/aboutthirdparty/nsIAboutThirdParty.idl
@@ -8,6 +8,19 @@
 [scriptable, uuid(d33ff086-b328-4ae6-aaf5-52d41aa5df38)]
 interface nsIAboutThirdParty : nsISupports
 {
+  /**
+   * ModuleType flags used by lookupModuleType.
+   */
+  const unsigned long ModuleType_Unknown = 1 << 0;
+  const unsigned long ModuleType_IME = 1 << 1;
+  const unsigned long ModuleType_ShellExtension = 1 << 2;
+
+  /**
+   * Returns a bitwise combination of the ModuleType_* flags
+   * for the given leaf name of a module.
+   */
+  unsigned long lookupModuleType(in AString aLeafName);
+
   /**
    * Posts a background task to collect system information and resolves
    * the returned promise when the task is finished.
diff --git a/toolkit/components/aboutthirdparty/tests/xpcshell/head.js b/toolkit/components/aboutthirdparty/tests/xpcshell/head.js
index 79714c5713a0..ede1d3cc738c 100644
--- a/toolkit/components/aboutthirdparty/tests/xpcshell/head.js
+++ b/toolkit/components/aboutthirdparty/tests/xpcshell/head.js
@@ -4,6 +4,7 @@
 
 "use strict";
 
+const kExtensionModuleName = "TestShellEx.dll";
 const kATP = Cc["@mozilla.org/about-thirdparty;1"].getService(
   Ci.nsIAboutThirdParty
 );
diff --git a/toolkit/components/aboutthirdparty/tests/xpcshell/test_aboutthirdparty.js b/toolkit/components/aboutthirdparty/tests/xpcshell/test_aboutthirdparty.js
index fa9a7c811ed3..109122b80472 100644
--- a/toolkit/components/aboutthirdparty/tests/xpcshell/test_aboutthirdparty.js
+++ b/toolkit/components/aboutthirdparty/tests/xpcshell/test_aboutthirdparty.js
@@ -3,6 +3,12 @@
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 
 add_task(async () => {
+  Assert.equal(
+    kATP.lookupModuleType(kExtensionModuleName),
+    0,
+    "lookupModuleType() returns 0 before system info is collected."
+  );
+
   // Make sure successive calls of collectSystemInfo() do not
   // cause anything bad.
   const kLoopCount = 100;
@@ -20,4 +26,28 @@ add_task(async () => {
       "All results from collectSystemInfo() are resolved."
     );
   }
+
+  Assert.equal(
+    kATP.lookupModuleType("SHELL32.dll"),
+    Ci.nsIAboutThirdParty.ModuleType_ShellExtension,
+    "Shell32.dll is always registered as a shell extension."
+  );
+
+  Assert.equal(
+    kATP.lookupModuleType(""),
+    Ci.nsIAboutThirdParty.ModuleType_Unknown,
+    "Looking up an empty string succeeds and returns ModuleType_Unknown."
+  );
+
+  Assert.equal(
+    kATP.lookupModuleType(null),
+    Ci.nsIAboutThirdParty.ModuleType_Unknown,
+    "Looking up null succeeds and returns ModuleType_Unknown."
+  );
+
+  Assert.equal(
+    kATP.lookupModuleType("invalid name"),
+    Ci.nsIAboutThirdParty.ModuleType_Unknown,
+    "Looking up an invalid name succeeds and returns ModuleType_Unknown."
+  );
 });
diff --git a/toolkit/locales/en-US/toolkit/about/aboutThirdParty.ftl b/toolkit/locales/en-US/toolkit/about/aboutThirdParty.ftl
index cef01d64d6d8..c7080d90c1a9 100644
--- a/toolkit/locales/en-US/toolkit/about/aboutThirdParty.ftl
+++ b/toolkit/locales/en-US/toolkit/about/aboutThirdParty.ftl
@@ -27,6 +27,12 @@ third-party-th-process = Process
 third-party-th-duration = Loading Duration (ms)
 third-party-th-status = Status
 
+third-party-tag-ime = IME
+    .title =
+        This type of module is loaded when you use a third-party IME.
+third-party-tag-shellex = Shell Extension
+    .title =
+        This type of module is loaded when you open the system file dialog.
 third-party-tag-background = Background
     .title =
         This module did not block the application because it was loaded
@@ -39,6 +45,8 @@ third-party-status-blocked = Blocked
 third-party-status-redirected = Redirected
 
 third-party-button-copy-to-clipboard = Copy raw data to clipboard
+third-party-button-reload = Reload with system info
+    .title = Reload with system information
 third-party-button-open =
     .title = Open file location…
 third-party-button-expand =