if ( !in_array(UTIL_File::getExtension($_FILES['attachment']['name']), array('jpeg', 'jpg', 'png', 'gif')) )
untested so use at your own risk. Someone else may want to validate that...
Remove , 'gif' from the line below, which is found in ow_system_plugins/base/controllers/attachment.php:
if ( !in_array(UTIL_File::getExtension($_FILES['attachment']['name']), array('jpeg', 'jpg', 'png', 'gif')) )
untested so use at your own risk. Someone else may want to validate that...
You may also want to update this line:
ow_system_plugins/base/controllers/media_panel.php
OW::getFeedback()->error("Invalid file type. Acceptable file types: JPG/PNG/GIF");
and also, in news feed is kinda weird... I cant attach .gif but i can attach .png still >.<