ActiveWindow is a Vim plugin that sets line numbers for only the active window. The fold column is expanded to prevent text from shifting. ActiveWindow respects the sign column and leaves the fold column at least as wide as it's original value.
If you want the cursorline to be enabled for only the active window, set
g:activewindow#cursorline = 1
Use a list of regex patterns for buffers you don't want affected by ActiveWindow.
For example, use the following to ignore NERDTree windows and any buffer containing "foo" in its name:
let g:activewindow#skip = ['^NERD_tree_*', 'foo']
g:activewindow#enable = 1
g:activewindow#cursorline = 0
g:activewindow#use_default_maps = 1
nmap <leader>a <plug>(activewindow-Toggle)
To make the active window stand out even more, make use of the StatusLine and StatusLineNC highlight groups.