+
+" Dynamically set format options, depending on where you are in a
+" mail, idea from Teemu Likonen:
+" http://groups.google.com/group/vim_use/msg/f59e5c1adc6be2b3
+
+let d_fo = &fo
+let s:defaults = 'setlocal tw=68 ts=2 sts=2 sw=2 fo='.d_fo
+execute s:defaults
+let b:MailAreaDetect=1
+
+"nnoremap <buffer> <LocalLeader>ma1 :call <SID>MailAreaDetect_On()
+" \ <bar> echo 'MailAreaDetect On'<CR>
+"nnoremap <buffer> <LocalLeader>ma0 :call <SID>MailAreaDetect_Off()
+" \ <bar> echo 'MailAreaDetect Off'<CR>
+
+nnoremap <buffer><silent> <F9> :call <SID>MailAreaDetect_Switch(0)<CR>
+inoremap <buffer><silent> <F9> <C-\><C-O>:call <SID>MailAreaDetect_Switch(1)<CR>
+
+function! s:MailAreaDetect_Switch(vmode)
+ if b:MailAreaDetect
+ silent call <SID>MailAreaDetect_Off()
+ let b:MailAreaDetect=0
+ echo 'MailAreaDetect Off'
+ if a:vmode
+ sleep 1
+ endif
+ else
+ silent call <SID>MailAreaDetect_On()
+ let b:MailAreaDetect=1
+ echo 'MailAreaDetect On'
+ if a:vmode
+ sleep 1
+ endif
+ endif
+endfu
+
+
+function! s:MailAreaDetect_On()
+ silent autocmd! MailAreaDetect CursorMoved,CursorMoved
+ \ <buffer> call <SID>AreaOptions()
+ let b:MailAreaDetect=1
+endfunction
+
+function! s:MailAreaDetect_Off()
+ silent autocmd! MailAreaDetect
+ execute s:defaults
+ let b:MailAreaDetect=0
+endfunction
+
+augroup MailAreaDetect
+ autocmd!
+ call <SID>MailAreaDetect_On()
+augroup END
+
+function! s:AreaOptions()
+ execute s:defaults
+ if <SID>CheckArea('\v^From( |: ).*\n','\v^$')
+ "echo 'Header'
+ setlocal fo-=a fo-=w fo-=t sts=0 sw=2 noet
+ elseif getline('.') =~ '\m^\s*>'
+ "echo 'Quotation'
+ setlocal fo-=a fo-=w
+ elseif <SID>CheckArea('\m^--- .*\n^+++ ','\v(^$|\n^-- $)')
+ "echo 'Patch'
+ setlocal fo-=a fo-=w fo-=t sts=0 sw=2 noet
+ elseif <SID>CheckArea('^-- $','^$')
+ "echo 'Signature'
+ setlocal fo-=a fo-=w fo-=t sts=0 sw=2 noet
+ else
+ "echo 'My text'
+ setlocal fo+=aw et
+ endif
+endfunction
+
+function! s:CheckArea(start, end)
+ return (search(a:start,'bcnW')-line('.')) >
+ \ (search(a:end,'bnW')-line('.'))
+endfunction