Improve window killer (Q) - close window if multiple windows to same buffer exist

vim/plugin/settings/window-killer.vim

@@ -2,7 +2,9 @@
 " (if there are multiple windows into the same buffer)
 " or kill the buffer entirely if it's the last window looking into that buffer
 function! CloseWindowOrKillBuffer()
-  if(bufwinnr('%')) > 1
+  let number_of_windows_to_this_buffer = len(filter(range(1, winnr('$')), "winbufnr(v:val) == bufnr('%')"))
+
+  if number_of_windows_to_this_buffer > 1
     wincmd c
   else
     bdelete