vim opening file in left split screen

Question

When i open a file from nerdtree or vimfiler, the file is opening in left slipt screen and nerdtree/vimfiler jumps to right split screen..i got this problem after replacing vundle with neobundle eventhough neobundle has nothing to do with nerdtree/vimfiler..here is my vimrc file https://github.com/rajanand02/dotfiles/blob/master/.vimrc

vim before opening a file

vim after opening a file from startify or from vimfiler/nerdtree

these are the settings releated to nerdtree/vimfiler

autocmd VimEnter * NERDTree
autocmd VimEnter * NERDTreeTabsOpen 
autocmd VimEnter * NERDTreeMirror
autocmd VimEnter * wincmd p

let g:vimfiler_as_default_explorer = 1
autocmd VimEnter * VimFilerExplorer
autocmd VimEnter * wincmd p

Answer 1

i solved the problem by removing Tiled Window Manager Plugin dwm.vim..i had this plugin before migrating from Vundle to NeoBundle but When i update vimrc with NeoBundle something went wrong with this plugin..i figured this by inlcuding all the plugins one by one..

Answer 2

You can swicth two existing windows with <C-w>x with x like exchange.