Fix #1404 - Do not show balloons when g:ale_set_balloons is 0. Add b:ale_set_balloons

autoload/ale/balloon.vim

@@ -2,6 +2,13 @@
 " Description: balloonexpr support for ALE.
 
 function! ale#balloon#MessageForPos(bufnr, lnum, col) abort
+    " Don't show balloons if they are disabled, or linting is disabled.
+    if !ale#Var(a:bufnr, 'set_balloons')
+    \|| !g:ale_enabled
+    \|| !getbufvar(a:bufnr, 'ale_enabled', 1)
+        return ''
+    endif
+
     let l:loclist = get(g:ale_buffer_info, a:bufnr, {'loclist': []}).loclist
     let l:index = ale#util#BinarySearch(l:loclist, a:bufnr, a:lnum, a:col)
 
@@ -13,7 +20,7 @@ function! ale#balloon#Expr() abort
 endfunction
 
 function! ale#balloon#Disable() abort
-    set noballooneval
+    set noballooneval balloonexpr=
 endfunction
 
 function! ale#balloon#Enable() abort

autoload/ale/toggle.vim

@@ -84,10 +84,6 @@ function! s:EnablePreamble() abort
 
     " Lint immediately, including running linters against the file.
     call ale#Queue(0, 'lint_file')
-
-    if g:ale_set_balloons
-        call ale#balloon#Enable()
-    endif
 endfunction
 
 function! s:DisablePostamble() abort
@@ -95,10 +91,6 @@ function! s:DisablePostamble() abort
     if g:ale_set_highlights
         call ale#highlight#UpdateHighlights()
     endif
-
-    if g:ale_set_balloons
-        call ale#balloon#Disable()
-    endif
 endfunction
 
 function! s:CleanupEveryBuffer() abort
@@ -121,9 +113,17 @@ function! ale#toggle#Toggle() abort
 
     if g:ale_enabled
         call s:EnablePreamble()
+
+        if g:ale_set_balloons
+            call ale#balloon#Enable()
+        endif
     else
         call s:CleanupEveryBuffer()
         call s:DisablePostamble()
+
+        if has('balloon_eval')
+            call ale#balloon#Disable()
+        endif
     endif
 
     call ale#toggle#InitAuGroups()