refactor the Refresh() method for tree nodes

create a oFileTreeNode#Refresh() and make sure that Refresh() is always
called for dir nodes

plugin/NERD_tree.vim

@@ -348,6 +348,10 @@ function! s:oTreeFileNode.New(path) dict
     endif
 endfunction
 
+"FUNCTION: oTreeFileNode.Refresh {{{3
+function! s:oTreeFileNode.Refresh() dict
+    call self.path.Refresh()
+endfunction
 "FUNCTION: oTreeFileNode.Rename {{{3
 "Calls the rename method for this nodes path obj
 function! s:oTreeFileNode.Rename(newName) dict
@@ -701,11 +705,15 @@ function! s:oTreeDirNode.OpenRecursively2(forceOpen) dict
 endfunction
 
 "FUNCTION: oTreeDirNode.Refresh {{{3
+unlet s:oTreeDirNode.Refresh
 function! s:oTreeDirNode.Refresh() dict
+    call self.path.Refresh()
+
+    "if this node was ever opened, refresh its children
+    if self.isOpen || !empty(self.children)
+        "go thru all the files/dirs under this node
         let newChildNodes = []
         let invalidFilesFound = 0
-
-    "go thru all the files/dirs under this node
         let dir = self.path
         let filesStr = globpath(dir.StrForGlob(), '*') . "\n" . globpath(dir.StrForGlob(), '.*')
         let files = split(filesStr, "\n")
@@ -717,17 +725,7 @@ function! s:oTreeDirNode.Refresh() dict
                     let path = s:oPath.New(i)
                     let newNode = self.GetChild(path)
                     if newNode != {}
-
-                    "if the existing node is a dir can be refreshed then
-                    "refresh it
-                    if newNode.path.isDirectory && (!empty(newNode.children) || newNode.isOpen == 1)
                         call newNode.Refresh()
-
-                    "if we have a filenode then refresh the path
-                    elseif newNode.path.isDirectory == 0
-                        call newNode.path.Refresh()
-                    endif
-
                         call add(newChildNodes, newNode)
 
                     "the node doesnt exist so create it
@@ -751,6 +749,7 @@ function! s:oTreeDirNode.Refresh() dict
         if invalidFilesFound
             call s:EchoWarning("some files could not be loaded into the NERD tree")
         endif
+    endif
 endfunction
 
 "FUNCTION: oTreeDirNode.RemoveChild {{{3