Skip automatic copen when height <= 0

copen and cwindow expect a positive number for the window height so we
can use the value 0 to state that the quickfix window should not be
opened or closed automatically
Allow to temporarily activate manual mode by :Copen 0

autoload/dispatch.vim

@@ -843,7 +843,7 @@ endfunction
 " Quickfix window {{{1
 
 function! dispatch#copen(bang, count) abort
-  if a:count != 0
+  if a:count != 9999999
     let g:dispatch_temporary_quickfix_height = a:count
   elseif has_key(g:, 'dispatch_temporary_quickfix_height')
     unlet g:dispatch_temporary_quickfix_height
@@ -901,6 +901,13 @@ endfunction
 function! s:cwindow(request, all, copen)
   call s:cgetfile(a:request, a:all)
   let height = get(g:, 'dispatch_temporary_quickfix_height', get(g:, 'dispatch_quickfix_height', 10))
+  if height <= 0
+    if a:copen ==# -2
+      " Show the user who explicitly called Copen that something was done
+      echo 'QuickFix list updated'
+    endif
+    return
+  endif
   let was_qf = s:is_quickfix()
   execute 'botright' (a:copen ? 'copen' : 'cwindow') height
   if !was_qf && s:is_quickfix() && a:copen !=# -2

plugin/dispatch.vim

@@ -25,7 +25,7 @@ command! -bang -nargs=* -complete=customlist,dispatch#command_complete Spawn
 command! -bang -nargs=* -complete=customlist,dispatch#command_complete Start
       \ execute dispatch#start_command(<bang>0, <q-args>)
 
-command! -bang -count -bar Copen call dispatch#copen(<bang>0, <count>)
+command! -bang -count=9999999 -bar Copen call dispatch#copen(<bang>0, <count>)
 
 function! DispatchComplete(id) abort
   return dispatch#complete(a:id)