I found the problem. In /templates/default/standard_text_editor.tpl is the following code:
{literal}
function openPhotoPanel() {
photoWindow=window.open('ubbthreads.php?ubb=photopost','photopanel','scrollbars=yes,resizable=yes,width=500,height=600');
if (photoWindow.opener == null) photoWindow.opener = self;
}
{/literal}
The problem: there iss missing the base dir in front of ubbthreads.php?ubb=photopost. For a workaround I hardcode it for me like this: /board/ubbthreads.php?ubb=photopost
This work.
But what ist the propper way to enter it inside a function? I try {$config.BASE_URL}/ubbthreads.php?ubb=photopost but this dont work. Who can help?