First of all, this constant's name is bad since it can conflict with other plugins', but this is the least concern.
I am changing the default path for wp-content by setting the correct WordPress constants. This worked well so far, except with NGG since it builds the wp-content path using (WIN)ABSPATH+'wp-content' which is basically incorrect.
The fix would be to make use of the correct WordPress constants in order to find wp-content directory.
An easier way I've found is to define WINABSPATH myself. This works, but it generates log messages since NGG attempts to redefine that constant (nggallery.php line 257).
Can you please replace the following code:
define('WINABSPATH', str_replace("\\", "/", ABSPATH) );
With this one:
if(!defined('WINABSPATH'))define('WINABSPATH', str_replace("\\", "/", ABSPATH) );