Teleport skill can be easily edited in levels.txt file (I'm not sure if that is the right txt file) which can be viewed/opened with any mpq editor. It's simply changing the one of 2 modes of teleporting. One is, as we have it now, through walls, and other is only through clean and walkable path (no walls that is).
Different Diablo 2 mods (I won't name them) also use that version of teleport. It's a work of few minutes to edit it.
Two simple steps for fixing ALL problems with a high-resolution DII patch:
Step 1: Add a mouse-capturing overlay to prevent people from clicking on things outside the normal 800x600 boundary(excluding the interface, of course).
Step 2: Increase the fog of war to hide enemies (and possibly dungeon entrances/waypoints) located beyond the same 800x600 boundary.
Seriously, it isn't that hard to scale resolution on a legacy game. If some people would just take five minutes to think about it, all of the so-called *problems* with higher resolutions would be solved with simple logic.
I've played DII at 1366x768 resolution on a 40" LCD, and the colors look vibrant and crisp, without any signs of age. The original artists did an amazing job on DII's game sprites, thus they are very scalable at high resolutions. Being able to play DII on a widescreen monitor, with a scalable interface, would easily breathe another 3 years back into this game.
I think it'd be kind of neat to have little "extra info" bars at the sides of widescreen monitors. Such as, on the left side, when the gameplay screen ends at the 800x600 boundary, you'd have your damage indicators, attack rating, life, mana, basically everything from the character screen except stat levels and experience. On the right you could have a quick-skill bar, or something like that. I'm not sure if the second example would give an edge to widescreen players, but I doubt it when you can press a button to bring up your skills anyways.
If teleport ends up nerfed in this regard then make it that clicking outside the teleport's range teleports you to its maximum range. It would suck if you click too far and instead of teleporting you get a prompt saying "skill is out of range" or something o.O.
As for higher resolution, I'd rather not see it in the current D2.
It would increase lag and slowdown, make the game even tinier, and would bring about a host of balancing issues outlined before.