Wall types
I think a couple new wall types would be a welcome addition to the game.
Currently we only have solid walls, with no walkthrough. IE Picture 1
Very useful would be to have 2 more, one with horizontal walkthough (IE Pic 2) and one with horizontal walkthough and up only jumpthrough. (IE Pic 3)
How hard would this be to code?
Ah forgot about the platforms, so scratch #3. I'll make a quick picture for my reasoning behind #2.
I want the Portals to be where the purple boxes are, and the steps up to be different levels, each that can be ignored and walked through, or jumped onto to get up to the entrance to the Temple.
(( <3 my epic paint skills 
))
I think there is a bit of confusion. NetGore implements #1 [Wall] (cannot occupy the same space as the wall, ever) and #3 [Platform] (the wall only stops you when you are falling down). #2, where you can't go up or down through it, is the one that seems awkward since, once you occupy the same area as it, it'll basically "hold" you. So if there is a floating platform, and you jump into it from the side, you'll get "caught" in, able to only move left or right, not jump or fall.
Damn, was real hope'in it was something you could do 
While we're talking about walls, thanks for adding it to the mapeditor's Grh editting. However, it could use some improvements, you can't move walls around and there's no outline? Could you make it so it acts the way you manipulate walls on a map please? That'd be awesome.
Nah. Being able to drag the corners is enough. I really don't want to do any more than that. Its not like you will ever need more than like 2-3 walls each, and usually just one wall total. Doing more work on it would just be clutter and a pretty big waste of time. But feel free to do it yourself.
If you want to move it, drag one side, then shrink the other. Problem solved. Or, you know, just enter the new coordinates.
There are already platforms, which only block downward movement. I probably won't ever add directional walls, though.
Horizontal only... seems a bit odd. Not sure how that'd be useful. It wouldn't be tough to add, but won't add it to the base engine unless someone can make a convincing argument on it being useful for many games.