It would be nice if there was some kind of "allow vertical walk" option in the "Platform" behavior, or simply such new behavior that you can apply with a checkbox on the "Tiled Background" you want to walk on. Of course, it would be set to disabled as default, but would be good if you could set the walking plane height in properties for the sprite. In other words, set the bottom of the walk area and scale or set the height ceiling to where the sprite can't walk above. This behavior would mean 8 directional movement in between the height area selected with the ability to still jump above it like platform is now. This or something equivalent to this is ideal for faking Z movement with the platformer behavior on a vertically fixed play area. This can be sort of accomplished now (inefficiently) with detectors and "8 Direction" behavior, but causes an already reported bug that crashes when jumping while moving up. There are a bit of things planned for future, but they are not going to happen until this is fixed.
Also, while it's not a priority, some improvements in the image editor would be nice. Make it as good as Paint should be efficient. Maybe it's just me, but the insert text icon doesn't work, but it looks like it's a planned feature or something (could it be that it can, I just haven't set up the fonts?) I really wouldn't need to use Paint Shop Pro 7 if it wasn't for this missing feature, but it looks like it's a future feature.. For fun you could check out these programs if you need ideas: Wood Woodshop (<- best 2D texture program I've tried using so far haven't used it much though.), PixelToolbox (decent little tool for making some quick tile textures or small pixel editing. Again, haven't used it much.) Inkscape (Awesome, yet simple toolset, doesn't lag my slow computer either.). As an honorable mention, GraphicsGale looks great for animations.
Edit: the program is called Wood WorkShop, excuse me.
Cheers,
manontherun