--- a/mail/base/content/mailWindowOverlay.xul
+++ b/mail/base/content/mailWindowOverlay.xul
@@ -344,21 +344,17 @@
   <key id="key_toggleRead" key="&markAsReadCmd.key;"                 oncommand="goDoCommand('cmd_markAsRead');"/>
   <key id="key_toggleFlagged" key="&markStarredCmd.key;"             oncommand="goDoCommand('cmd_markAsFlagged');"/>
   <key id="key_markJunk" key="&markAsJunkCmd.key;"                   oncommand="goDoCommand('cmd_markAsJunk');"/>
   <key id="key_markNotJunk" key="&markAsNotJunkCmd.key;"             oncommand="goDoCommand('cmd_markAsNotJunk');"
        modifiers="shift"/>
 
   <key id="key_groupBySort" key="&groupBySortCmd.key;" oncommand="MsgGroupBySort();"/>
 
-#ifdef MOZ_WIDGET_GTK2
-  <key id="key_markAllRead" key="&markAllReadCmd.key;"               oncommand="goDoCommand('cmd_markAllRead');" modifiers="shift"/>
-#else
   <key id="key_markAllRead" key="&markAllReadCmd.key;"               oncommand="goDoCommand('cmd_markAllRead');" modifiers="accel, shift"/>
-#endif
 
   <key id="key_markThreadAsRead" key="&markThreadAsReadCmd.key;"     oncommand="goDoCommand('cmd_markThreadAsRead')"/>
   <key id="key_markReadByDate" key="&markReadByDateCmd.key;"         oncommand="goDoCommand('cmd_markReadByDate')"/>
   <key id="key_nextMsg" key="&nextMsgCmd.key;"                       oncommand="goDoCommand('cmd_nextMsg')"/>
   <key id="key_nextUnreadMsg" key="&nextUnreadMsgCmd.key;"           oncommand="goDoCommand('cmd_nextUnreadMsg')"/>
   <key id="key_expandAllThreads" key="&expandAllThreadsCmd.key;"     oncommand="goDoCommand('cmd_expandAllThreads')"/>
   <key key="&expandAllThreadsCmd.key;" modifiers="shift"             oncommand="goDoCommand('cmd_expandAllThreads')"/>
   <key id="key_collapseAllThreads" key="&collapseAllThreadsCmd.key;" oncommand="goDoCommand('cmd_collapseAllThreads')"/>

--- a/mailnews/base/resources/content/unix/platformMailnewsOverlay.xul
+++ b/mailnews/base/resources/content/unix/platformMailnewsOverlay.xul
@@ -7,18 +7,14 @@
          xmlns="http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul">
 
     <!-- Delete Key -->
     <key id="key_shiftDelete" keycode="VK_DELETE" modifiers="shift" command="cmd_shiftDelete"/>
 
     <!-- Select Thread -->
     <key id="key_selectThread" modifiers="alt,shift"/>
 
-    <!-- We have to override the keybinding for mark all read since GTK2
-         doesn't allow any Ctrl+Shift+[0-9][A-F] shortcuts. -->
-    <key id="key_markAllRead" key="&markAllReadCmdUnix.key;"/>
-
     <!-- Find -->
     <keyset id="mailKeys">
         <key keycode="VK_F19" oncommand="goDoCommand('cmd_find')"/>
     </keyset>
 
 </overlay>

--- a/suite/locales/en-US/chrome/common/help/shortcuts-mailnews.xhtml
+++ b/suite/locales/en-US/chrome/common/help/shortcuts-mailnews.xhtml
@@ -260,17 +260,17 @@
     <td>C</td>
     <td>C</td>
     <td>C</td>
   </tr>
   <tr>
     <td>Mark All Messages in Selected Folder As Read</td>
     <td>Ctrl+Shift+C</td>
     <td>Cmd+Shift+C</td>
-    <td>Ctrl+Shift+M</td>
+    <td>Ctrl+Shift+C</td>
   </tr>
   <tr>
     <td>Flag Message</td>
     <td>I</td>
     <td>I</td>
     <td>I</td>
   </tr>
   <tr>

--- a/suite/locales/en-US/chrome/mailnews/messenger.dtd
+++ b/suite/locales/en-US/chrome/mailnews/messenger.dtd
@@ -417,17 +417,16 @@
 <!ENTITY markThreadAsReadCmd.accesskey "T">
 <!ENTITY markThreadAsReadCmd.key "r">
 <!ENTITY markReadByDateCmd.label "As Read by Date…">
 <!ENTITY markReadByDateCmd.accesskey "D">
 <!ENTITY markReadByDateCmd.key "c">
 <!ENTITY markAllReadCmd.label "All Read">
 <!ENTITY markAllReadCmd.accesskey "A">
 <!ENTITY markAllReadCmd.key "c">
-<!ENTITY markAllReadCmdUnix.key "m">
 <!ENTITY markFlaggedCmd.label "Flag">
 <!ENTITY markFlaggedCmd.accesskey "F">
 <!ENTITY markFlaggedCmd.key "i">
 <!ENTITY markAsJunkCmd.label "As Junk">
 <!ENTITY markAsJunkCmd.accesskey "J">
 <!ENTITY markAsJunkCmd.key "j">
 <!ENTITY markAsNotJunkCmd.label "As Not Junk">
 <!ENTITY markAsNotJunkCmd.accesskey "N">