Attempt at fix for #947

autoload/vimtex/view/common.vim

@@ -151,14 +151,24 @@ function! s:xwin_template.xwin_exists() dict " {{{1
   " If xwin_id is unset, check if matching viewer windows exist
   "
   if self.xwin_id == 0
-    let cmd = 'xdotool search --name ' . fnamemodify(self.out(), ':t')
-    let result = split(system(cmd), '\n')
-    if len(result) > 0
-      let self.xwin_id = result[-1]
-    endif
+    let pid = has_key(self, 'get_pid') ? self.get_pid() : 0
+    let cmd = 'xdotool search'
+          \ . (pid > 0 ? ' --all --pid ' . pid : '')
+          \ . ' --name ' . fnamemodify(self.out(), ':t')
+    let ids = split(system(cmd), '\n')
+
+    let ids_already_used = filter(map(deepcopy(vimtex#state#list_all()),
+          \ "get(get(v:val, 'viewer', {}), 'xwin_id')"), 'v:val > 0')
+
+    for id in ids
+      if index(ids_already_used, id) < 0
+        let self.xwin_id = id
+        break
+      endif
+    endfor
   endif
 
-  return (self.xwin_id > 0)
+  return self.xwin_id > 0
 endfunction
 
 " }}}1

autoload/vimtex/view/zathura.vim

@@ -45,6 +45,7 @@ function! s:zathura.start(outfile) dict " {{{1
   let self.process = vimtex#process#start(l:cmd)
 
   call self.xwin_get_id()
+  let self.outfile = a:outfile
 endfunction
 
 " }}}1
@@ -58,6 +59,7 @@ function! s:zathura.forward_search(outfile) dict " {{{1
   let l:cmd .= ' ' . vimtex#util#shellescape(a:outfile)
   call vimtex#process#run(l:cmd)
   let self.cmd_forward_search = l:cmd
+  let self.outfile = a:outfile
 endfunction
 
 " }}}1
@@ -113,6 +115,14 @@ function! s:zathura.latexmk_append_argument() dict " {{{1
   return cmd
 endfunction
 
+" }}}1
+function! s:zathura.get_pid() dict " {{{1
+  let cmd = 'pgrep -nf "zathura.*'
+        \ . escape(get(self, 'outfile', self.out()), '~\%.') . '"'
+  let pid = str2nr(system(cmd)[:-2])
+  return pid > 0 ? pid : 0
+endfunction
+
 " }}}1
 
 " vim: fdm=marker sw=2