this is a draft for a Vim plugin to keep my plugins in the "same" window

panel.vim

if exists('loaded_panel') 
   finish 
endif 
let loaded_panel = 1 

" TODO maybe move configuration to .vimrc
" TODO when a width of 0 is given -> ask panel for size; introduce min/max width
let s:panels_config = { 'files':{'run':'Files', 'width':60}, 
                      \ 'buffers':{'run':'Buffers', 'width':20}, 
                      \ 'tags':{'run':'Tags', 'width':30}, 
                      \ 'sessions':{'run':'Sessions', 'width':15}, 
                      \ 'misspellings':{'run':'Misspellings', 'width':25}} 

" init value in case PanelToggle is called first
let s:panel = "files"

function! Files() 
   let l:content="files panel"
   put! =l:content
endfunction 

function! Buffers() 
   let l:content="buffers panel"
   put! =l:content
endfunction 

function! Tags() 
   let l:content="tags panel"
   put! =l:content
endfunction 

function! Sessions() 
   let l:content="sessions panel"
   put! =l:content
endfunction 

function! Misspellings() 
   let l:content="misspellings panel"
   put! =l:content
endfunction 

function! PanelToggle()
   let bufnr = bufwinnr("__PANEL__") 
   if bufnr == -1 
      silent! vsplit __PANEL__ 
      setlocal buftype=nofile 
      setlocal bufhidden=wipe 
      setlocal noswapfile 
      setlocal nowrap 
      setlocal nobuflisted 
      setlocal nonumber 
      setlocal nospell 
      setlocal statusline=
      exec 'vertical resize '.s:panels_config[s:panel]['width'] 
      exec 'call '.s:panels_config[s:panel]['run'].'()' 
      nnoremap <buffer> <silent> q :bwipeout!<CR> 
      setlocal nomodifiable 
   else 
      bwipeout! __PANEL__ 
   endif 
endfunction

function! Panel(tool)
   let bufnr = bufwinnr("__PANEL__") 
   if bufnr == -1 
      silent! vsplit __PANEL__ 
      setlocal buftype=nofile 
      setlocal bufhidden=wipe 
      setlocal noswapfile 
      setlocal nowrap 
      setlocal nobuflisted 
      setlocal nonumber 
      setlocal nospell 
      setlocal statusline=
      let s:panel = a:tool 
      exec 'vertical resize '.s:panels_config[s:panel]['width'] 
      exec 'call '.s:panels_config[s:panel]['run'].'()' 
      nnoremap <buffer> <silent> q :bwipeout!<CR> 
      setlocal nomodifiable 
   else 
      if s:panel != a:tool 
         let s:panel = a:tool 
         setlocal modifiable 
         %d
         exec 'vertical resize '.s:panels_config[s:panel]['width'] 
         exec 'call '.s:panels_config[s:panel]['run'].'()' 
         nnoremap <buffer> <silent> q :bwipeout!<CR> 
         setlocal nomodifiable 
      else 
         if bufname("%") == "__PANEL__" 
            bwipeout! __PANEL__ 
         else 
            execute bufnr . 'wincmd w' 
            " TODO remove resize command; find out why Vim is resizing the window on its own
            exec 'vertical resize '.s:panels_config[s:panel]['width'] 
         endif 
      endif 
   endif 
endfunction

" TODO create <SID>commands and make functions local to script; remove mappings
nnoremap <F1> :call PanelToggle()<CR> 
nnoremap <F2> :call Panel('files')<CR> 
nnoremap <F3> :call Panel('buffers')<CR> 
nnoremap <F4> :call Panel('tags')<CR> 
nnoremap <F5> :call Panel('sessions')<CR> 
nnoremap <F6> :call Panel('misspellings')<CR>