diff --git a/toolkit/mozapps/downloads/content/unknownContentType.xul b/toolkit/mozapps/downloads/content/unknownContentType.xul
index 8af7498a5077..34ea8cb3b3f3 100644
--- a/toolkit/mozapps/downloads/content/unknownContentType.xul
+++ b/toolkit/mozapps/downloads/content/unknownContentType.xul
@@ -14,10 +14,11 @@
   %uctDTD;
   <!ENTITY % scDTD SYSTEM "chrome://mozapps/locale/downloads/settingsChange.dtd" >
   %scDTD;
-]>            
+]>
 
 <dialog id="unknownContentType"
         xmlns="http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul"
+        xmlns:html="http://www.w3.org/1999/xhtml"
         onload="dialog.initDialog();" onunload="if (dialog) dialog.onCancel();"
 #ifdef XP_WIN
         style="width: 36em;"
@@ -28,10 +29,12 @@
         persist="screenX screenY"
         aria-describedby="intro location whichIs type from source unknownPrompt">
 
-
   <stringbundle id="strings" src="chrome://mozapps/locale/downloads/unknownContentType.properties"/>
 
-  <vbox flex="1" id="container">  
+  <script src="chrome://global/content/globalOverlay.js"/>
+  <script src="chrome://global/content/editMenuOverlay.js"/>
+
+  <vbox flex="1" id="container">
     <description id="intro">&intro2.label;</description>
     <separator class="thin"/>
     <hbox align="start" class="small-indent">
@@ -41,7 +44,7 @@
         <separator class="thin"/>
         <hbox align="center">
           <label id="whichIs" value="&whichIs.label;"/>
-          <textbox id="type" class="plain" readonly="true" flex="1" noinitialfocus="true"/>
+          <html:input id="type" class="plain" readonly="readonly" noinitialfocus="true"/>
         </hbox>
         <hbox align="center">
           <label value="&from.label;" id="from"/>
@@ -49,7 +52,7 @@
         </hbox>
       </vbox>
     </hbox>
-    
+
     <separator class="thin"/>
 
     <hbox align="center" id="basicBox" collapsed="true">
@@ -74,16 +77,16 @@
             </hbox>
           </deck>
         </hbox>
-        
+
         <radio id="save" label="&saveFile.label;" accesskey="&saveFile.accesskey;"/>
-      </radiogroup> 
+      </radiogroup>
       <separator class="thin"/>
       <hbox class="small-indent">
         <checkbox id="rememberChoice" label="&rememberChoice.label;"
                   accesskey="&rememberChoice.accesskey;"
                   oncommand="dialog.toggleRememberChoice(event.target);"/>
       </hbox>
-      
+
       <separator/>
 #ifdef XP_UNIX
       <description id="settingsChange" hidden="true">&settingsChangePreferences.label;</description>
@@ -93,7 +96,7 @@
       <separator class="thin"/>
     </vbox>
   </vbox>
-  
+
   <menulist id="openHandler" flex="1">
     <menupopup id="openHandlerPopup" oncommand="dialog.openHandlerCommand();">
       <menuitem id="defaultHandler" default="true" crop="right"/>
diff --git a/toolkit/themes/osx/mozapps/downloads/unknownContentType.css b/toolkit/themes/osx/mozapps/downloads/unknownContentType.css
index 28d01b57afb2..0d8b353dd8bf 100644
--- a/toolkit/themes/osx/mozapps/downloads/unknownContentType.css
+++ b/toolkit/themes/osx/mozapps/downloads/unknownContentType.css
@@ -10,21 +10,19 @@ description {
   font-weight: bold;
 }
 
-.plain {
-  background-color: transparent;
-  background-image: none;
-  border: none;
-}
-
 #contentTypeImage {
   margin-right: 3px;
   width: 16px;
 }
 
+#type {
+  -moz-box-flex: 1;
+}
+
 #container > .small-indent {
-  margin-left: 0px;
+  margin-left: 0;
 }
 
 .small-indent label {
-  margin-left: 0px;
+  margin-left: 0;
 }
diff --git a/toolkit/themes/windows/mozapps/downloads/unknownContentType.css b/toolkit/themes/windows/mozapps/downloads/unknownContentType.css
index 0682146539d9..0865f8ac8fac 100644
--- a/toolkit/themes/windows/mozapps/downloads/unknownContentType.css
+++ b/toolkit/themes/windows/mozapps/downloads/unknownContentType.css
@@ -2,9 +2,12 @@
  * License, v. 2.0. If a copy of the MPL was not distributed with this
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 
+#type {
+  -moz-box-flex: 1;
+}
 
 #from {
-  margin-top: 1px; 
+  margin-top: 1px;
 }
 
 #location {
@@ -14,18 +17,15 @@
 #contentTypeImage {
   height: 16px;
   width: 16px;
-  margin-top: 0px;
-  margin-bottom: 0px;
-  margin-inline-start: 0px;
+  margin-block: 0;
+  margin-inline-start: 0;
   margin-inline-end: 5px;
 }
 
 .small-indent {
-  margin-inline-start: 15px; 
-  margin-inline-end: 15px;
+  margin-inline: 15px;
 }
 
 .small-indent label {
-  margin-inline-start: 0px; 
+  margin-inline-start: 0;
 }
-