diff --git a/runtime/autoload/tohtml.vim b/runtime/autoload/tohtml.vim
index 8a51b35..e929db3 100644
--- a/runtime/autoload/tohtml.vim
+++ b/runtime/autoload/tohtml.vim
@@ -1,11 +1,22 @@
 " Vim autoload file for the tohtml plugin.
-" Maintainer: Bram Moolenaar <Bram@vim.org>
-" Last Change: 2010 Jul 11
+" Maintainer: Ben Fritz <fritzophrenic@gmail.com>
+" Last Change: 2010 Jul 15
 "
-" Diff2HTML() added by Christian Brabandt <cb@256bit.org>
+" Additional contributors:
+"
+"             Original by Bram Moolenaar <Bram@vim.org>
+"             Diff2HTML() added by Christian Brabandt <cb@256bit.org>
+"
+"             See Mercurial change logs for more!
+ 
+" this file uses line continuations
+let s:cpo_sav = &cpo
+set cpo-=C
 
 func! tohtml#Convert2HTML(line1, line2)
-  if !&diff || exists("g:diff_one_file")
+  let old_vals = tohtml#OverrideUserSettings()
+
+  if !&diff || exists("g:html_diff_one_file")
     if a:line2 >= a:line1
       let g:html_start_line = a:line1
       let g:html_end_line = a:line2
@@ -17,27 +28,34 @@
   else
     let win_list = []
     let buf_list = []
-    windo | if (&diff) | call add(win_list, winbufnr(0)) | endif
+    windo | if &diff | call add(win_list, winbufnr(0)) | endif
     let save_hwf = exists("g:html_whole_filler")
     let g:html_whole_filler = 1
+    let g:html_diff_win_num = 0
     for window in win_list
       exe ":" . bufwinnr(window) . "wincmd w"
       let g:html_start_line = 1
       let g:html_end_line = line('$')
+      let g:html_diff_win_num += 1
       runtime syntax/2html.vim
       call add(buf_list, bufnr('%'))
+      "exec '%s#<span id=''\zsfold\d\+\ze''#win'.win_num.'\0#ge'
     endfor
+    unlet g:html_diff_win_num
     if !save_hwf
       unlet g:html_whole_filler
     endif
     call tohtml#Diff2HTML(win_list, buf_list)
   endif
 
+  call tohtml#RestoreUserSettings(old_vals)
+
   unlet g:html_start_line
   unlet g:html_end_line
 endfunc
 
 func! tohtml#Diff2HTML(win_list, buf_list)
+  " TODO: add logic for xhtml
   let style = []
   let html = []
   call add(html, '<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"')
@@ -45,12 +63,14 @@
   call add(html, '<html>')
   call add(html, '<head>')
   call add(html, '<title>diff</title>')
-  call add(html, '<meta name="Generator" content="Vim/7.3">')
-  "call add(html, '<meta http-equiv="content-type" content="text/html; charset=iso-8859-1">')
+  call add(html, '<meta name="Generator" content="Vim/'.v:version/100.'.'.v:version%100.'">')
+  " TODO: copy or move encoding logic from 2html.vim so generated markup can
+  " validate without warnings about encoding
+
   call add(html, '</head>')
   call add(html, '<body>')
   call add(html, '<table border="1" width="100%">')
-  "call add(html, '<font face="monospace">')
+
   call add(html, '<tr>')
   for buf in a:win_list
     call add(html, '<th>'.bufname(buf).'</th>')
@@ -61,6 +81,10 @@
     let temp = []
     exe bufwinnr(buf) . 'wincmd w'
 
+    " If text is folded because of user foldmethod settings, etc. we don't want
+    " to act on everything in a fold by mistake.
+    setlocal nofoldenable
+
     " Grab the style information.  Some of this will be duplicated...
     1
     let style_start = search('^<style type="text/css">')
@@ -78,12 +102,15 @@
     let temp = getline(1,'$')
     " undo deletion of start and end part
     " so we can later save the file as valid html
+    " TODO: restore using grabbed lines if undolevel is 1?
     normal 2u
-    call add(html, '<td nowrap valign="top">')
+    call add(html, '<td nowrap valign="top"><div>')
     let html += temp
-    call add(html, '</td>')
+    call add(html, '</div></td>')
 
     " Close this buffer
+    " TODO: the comment above says we're going to allow saving the file
+    " later...but here we discard it?
     quit!
   endfor
 
@@ -94,18 +121,122 @@
 
   let i = 1
   let name = "Diff" . ".html"
+  " Find an unused file name if current file name is already in use
   while filereadable(name)
     let name = substitute(name, '\d*\.html$', '', '') . i . ".html"
     let i += 1
-  endw
-  exe "new " . name
-  set modifiable
+  endwhile
+  exe "topleft new " . name
+  setlocal modifiable
+
+  " just in case some user autocmd creates content in the new buffer, make sure
+  " it is empty before proceeding
+  %d
   call append(0, html)
+
   if len(style) > 0
     1
-    let style_start = search('^</head>')
-    call append(style_start, '</style>')
-    call append(style_start, style)
-    call append(style_start, '<style type="text/css">')
+    let style_start = search('^</head>')-1
+
+    " Insert javascript to toggle matching folds open and closed in all windows,
+    " if dynamic folding is active.
+    if exists("g:html_dynamic_folds")
+      call append(style_start, [
+            \  "<script type='text/javascript'>",
+            \  "  <!--",
+            \  "  function toggleFold(objID)",
+            \  "  {",
+            \  "    for (win_num = 1; win_num <= 2; win_num++)",
+            \  "    {",
+            \  "      var fold;",
+            \  '      fold = document.getElementById("win"+win_num+objID);',
+            \  "      if(fold.className == 'closed-fold')",
+            \  "      {",
+            \  "        fold.className = 'open-fold';",
+            \  "      }",
+            \  "      else if (fold.className == 'open-fold')",
+            \  "      {",
+            \  "        fold.className = 'closed-fold';",
+            \  "      }",
+            \  "    }",
+            \  "  }",
+            \  "  -->",
+            \  "</script>"
+            \ ])
+    endif
+
+    " Insert styles from all the generated html documents and additional styles
+    " for the table-based layout of the side-by-side diff. The diff should take
+    " up the full browser window (but not more), and be static in size,
+    " horizontally scrollable when the lines are too long. Otherwise, the diff
+    " is pretty useless for really long lines.
+    if exists("g:html_use_css")
+      call append(style_start, [
+            \ '<style type="text/css">']+
+            \  style+[
+            \ '<!--',
+            \ 'table { table-layout: fixed; }',
+            \ 'html, body, table, tbody { width: 100%; margin: 0; padding: 0; }',
+            \ 'th, td { width: '.printf("%.1f",100.0/len(a:win_list)).'%; }',
+            \ 'td div { overflow: auto; }',
+            \ '-->',
+            \  '</style>'
+            \ ])
+    endif
   endif
 endfunc
+
+func! tohtml#OverrideUserSettings()
+  let old_settings = {}
+  " make copies of the user-defined settings that we may overrule
+  let old_settings.html_dynamic_folds = exists("g:html_dynamic_folds")
+  let old_settings.html_hover_unfold = exists("g:html_hover_unfold")
+  let old_settings.html_use_css = exists("g:html_use_css")
+
+  " hover opening implies dynamic folding
+  if exists("g:html_hover_unfold")
+    let g:html_dynamic_folds = 1
+  endif
+
+  " dynamic folding with no foldcolumn implies hover opens
+  if exists("g:html_dynamic_folds") && exists("g:html_no_foldcolumn")
+    let g:html_hover_unfold = 1
+  endif
+
+  " ignore folding overrides dynamic folding
+  if exists("g:html_ignore_folding") && exists("g:html_dynamic_folds")
+    unlet g:html_dynamic_folds
+  endif
+
+  " dynamic folding implies css
+  if exists("g:html_dynamic_folds")
+    let g:html_use_css = 1
+  endif
+
+  return old_settings
+endfunc
+
+func! tohtml#RestoreUserSettings(old_settings)
+  " restore any overridden user options
+  if a:old_settings.html_dynamic_folds
+    let g:html_dynamic_folds = 1
+  else
+    unlet! g:html_dynamic_folds
+  endif
+  if a:old_settings.html_hover_unfold
+    let g:html_hover_unfold = 1
+  else
+    unlet! g:html_hover_unfold
+  endif
+  if a:old_settings.html_use_css
+    let g:html_use_css = 1
+  else
+    unlet! g:html_use_css
+  endif
+endfunc
+
+let &cpo = s:cpo_sav
+unlet s:cpo_sav
+
+" Make sure any patches will probably use consistent indent
+"   vim: sw=2 sts=2 et