I just recently read a post about avoid duplicating official plugins, and I completly understood why.
But, before I noticed that post, I did posted a mod behaviour (of platform) and I actually seen another one.
Well, my suggestion is to add the functionality of Filtering Solids (and jumpthrus) by Layer,
I am very convinced about it's utility and the ease of implementation, to the point I was able to do it in a few hours without knowing the code, so it must be very easy for you.
?What I mean about this Filter? ?Do you know McMillen's Time Fcuk? Its basically a platformer where two "level" exist in parallel, one over the other, and you can switch between those... In that game, there is only the player, so, it's not more than disabling and enabling the solids... but If you have the same idea but multiplayer or enemies using "Platform" then it becomes quite problematic.
What I did is add a boolean, that, when its true it will check if Layer of Platform it's same as Layer of solid object, and ignore if false (this occurs in the for loop that runs throug all solids, before the actual collision checking)
Please, take a look at it, i'm sure you will understan better when you read the code (care, it's ugly, and awfully commented):
CODE: mediafire.com/download.php
EXAMPLES: mediafire.com/download.php