Patching filepicker for new tree widget. part of bug 30511. r=hyatt.

xpfe/components/filepicker/res/content/filepicker.js

@@ -195,6 +195,7 @@ function dirSort(e1, e2)
 function createTree(parentElement, dirArray)
 {
   var treeChildren = document.createElement("treechildren");
+  treeChildren.setAttribute("flex", "1");
 
   var len = dirArray.length;
   var file;

xpfe/components/filepicker/res/content/filepicker.xul

@@ -25,9 +25,11 @@
 
 <box align="horizontal" flex="1">
   <tree id="directoryList" onclick="onClick(event);" flex="1">
-    <treecol/>
-    <treecol/>
-    <treecol/>
+    <treecolgroup>
+      <treecol flex="1"/>
+      <treecol flex="1"/>
+      <treecol flex="1"/>
+    </treecolgroup>
     <treehead>
       <treerow>
         <treecell class="treecell-header" value="Name"/>