After patching my dokuwiki installation (see bug report "
FS#581 — More than one dokuwiki installations on the same server.") my dokuwiki installation shows and hides images after browser reload. I have patched this by commenting a line in lib/exe/fetch.php:
line 79:
-> header('Cache-Control: private, must-revalidate, post-check=0, pre-check=0');
<- // header('Cache-Control: private, must-revalidate, post-check=0, pre-check=0');
Althought this one is a very dirty hack, it has done its job for my installation.