diff --git a/suite/common/pref/pref-applications.xul b/suite/common/pref/pref-applications.xul
index f2e6cb797353..099e7fc43ef6 100644
--- a/suite/common/pref/pref-applications.xul
+++ b/suite/common/pref/pref-applications.xul
@@ -48,8 +48,10 @@
     <box orient="vertical">
       <text class="label" value="&fileTypes.label;"/>
       <tree id="appTree" class="inset" flex="1">
-        <treecol/>
-        <treechildren>
+        <treecolgroup>
+          <treecol flex="1"/>
+        </treecolgroup>
+        <treechildren flex="1">
           <treeitem>
             <treerow>
               <treecell value="&aimLaunchSelect.label;"/>
diff --git a/suite/common/pref/pref-policies.xul b/suite/common/pref/pref-policies.xul
index 8e7d18b0931f..663e01fd23fa 100644
--- a/suite/common/pref/pref-policies.xul
+++ b/suite/common/pref/pref-policies.xul
@@ -27,9 +27,11 @@
     <text class="label" value="&policies.label;"/>
     <box>
       <tree id="zones" class="inset" flex="1">
-        <treecol/>
+        <treecolgroup>
+          <treecol flex="1"/>
+        </treecolgroup>
         
-        <treechildren id="zoneChildren">  
+        <treechildren id="zoneChildren" flex="1">  
           <treeitem open="true">
             <treerow>
               <treecell value="&default.label;"/>
diff --git a/suite/common/pref/pref-smart_browsing.xul b/suite/common/pref/pref-smart_browsing.xul
index 3d344f478238..a69698b3fb1c 100644
--- a/suite/common/pref/pref-smart_browsing.xul
+++ b/suite/common/pref/pref-smart_browsing.xul
@@ -165,8 +165,10 @@
       <rows>
         <row>
           <tree class="inset" id="disabledDomains" multiple="true" onkeyup="treeHandleEvent(event)">
-            <treecol/>   
-            <treechildren id="disabledKids"/>
+            <treecolgroup>
+              <treecol flex="1"/>   
+            </treecolgroup>
+            <treechildren id="disabledKids" flex="1"/>
           </tree>
           <box autostretch="never" valign="top">
             <button class="dialog" id="removeDomain" value="&removeDomain.label;" accesskey="&removeDomain.accesskey;"
diff --git a/suite/common/pref/pref-smartupdate.xul b/suite/common/pref/pref-smartupdate.xul
index 57c91b783c17..645f1858f71c 100644
--- a/suite/common/pref/pref-smartupdate.xul
+++ b/suite/common/pref/pref-smartupdate.xul
@@ -35,8 +35,10 @@
     <html:div class="hspace-both">&selectUninstall.label;</html:div>
     <box class="hspace-both vspace" align="horizontal" flex="100%" style="width: 93%; height: 100%">
       <tree id="smartUpdatePackages" class="inset" flex="100%" style="height: 40%;">
-        <treecol/>
-        <treechildren>
+        <treecolgroup>
+          <treecol flex="1"/>
+        </treecolgroup>
+        <treechildren flex="1">
           <treeitem>
             <treerow>
               <treeitem/>