Shulla

You might be able to guess it, but the game sure can't. It changes all new biomes when loaded in an old version to plains biomes, but does not change the preset, so it will crash if you load any new chunks. I just think that it should at least keep the biome type somewhere for when you load it in the new version again, and not just for new chunks. I know that I accidentally join worlds that are newer than the version that I am playing, particularly when I switch between worlds and versions, as the latest played worlds are at the top by default.
I think that the biome not saving can be fixed by keeping a log of what the biome ID is when leaving a game, and keep that stored so that the world can go back to that biome later. This could also apply to non-superflat worlds. Now that I think about it, the preset shoudl be able to keep the biome anyway, but I know that some custom map makers load superflat worlds and change the biome of certain areas, so just blanketing the whole world with that preset biome ID every load could be bad, so the former idea has some significance,
As for the crashing, possibly prevent those new chunks from being generated, generate them and regenerate them properly after, or just generate them as default plains and change the biome ID to the preset.

I cannot post a crash report for the latest versions, as the latest versions do not crash yet but will if/when any more new biomes are added after them.
For example, 1.7 added new biomes and so made this happen to 1.6. If any new biomes are added later, 1.7 will crash as well. I tried to explain this at the bottom of the description, but I'm not that good at making things easy to comprehend.

If that is the case, which part of the preset is invalid? As far as I know, all blocks are as they should be. Just like it is possible to use decaying leaves, carrot blocks should not have to be player placed. If a carrot block counts as a "technical" block, why did they even remove the item forms in the first place? It is not known to me the reason, if any. Even if the item forms were removed, it should be fixed where the game wouldn't try to render the item sprites in the menu and cause crashes. I believe that that is a bug and so this is actually a bug that needs fixing. Please, either get this bug fixed or explain what I did wrong, as I cannot see any errors of mine. Thank you.

Happens to me quite frequently, just didn't report it because it isn't that big of a deal for me. I have figured out that if you go into the menu and then to the options, and you change the music sound at all, (Maybe that last part isn't even required.) the songs end and [a] new one(s) will not begin for a bit.

Hmmm. I don't know then. Maybe try allocating more memory to Minecraft, or maybe try waiting at the pause screen for like 30 seconds before exiting. If those don't work, then I guess just wait for an admin to tell if it's a bug or not.

Are you sure that you are pressing ESC and then closing the world? When you press ESC in SP, which is what I assume that you're playing in, it saves the world so that you can just press the title screen button immediately. If you close it by other means such as task manager or alt + f4, then it might not save it all. This may or may not be the case, but I hope that it works next time.

This is a technical support issue, as is almost every other issue here. The definition of technical support is : A service provided by a hardware or software company that provides registered users with help and advice about their products.
Mojang has this bug tracker, which is a service that provides registered users with help. In 13w38 A, B, and C, the message "Failed to login: Failed to log you in 😞" appeared. This prevents me from logging in, and is not related to my account or the current Mojang services. When I upgraded to 13W39 A and B, the same thing happened, except that it displayed "Failed to login: authentication are currently down for maintenance" instead. On the Mojang website's status checker, it showed all of the services as up and running. This has also happened to a few other people that I know, and was angering them as well. After hours of testing, I discovered that it only displayed these messages if I booted the game and directly joined a server. I learned that waiting 5-10 minutes after booting the start menu would allow us to connect to a server, and also that editing and saving our profiles fixed it for that one login only. Anyway, thanks for helping. I had forgotten that the default language was British English, and furthermore had no idea that British English was that different from standard English in the US. Anyway, just adding this comment here to help anyone else who had this problem, although I hope that it is fixed completely so that we don't have to wait 5 minutes each time we login. Maybe you could mark the resolution as fixed instead of invalid?

I remember looking at the code in 1.5.2 for leaves for a mod, and I remember seeing code about downfall passing though leaves, and I don't remember there being any mention of snow. Just trying to help.

If this is intended, maybe you might want to mark the resolution as such.

Also, I'm pretty sure that tunneler's dream is supposed to be extreme hills because of emeralds.

This was resolved by 13w37 and Minecraft 1.6.3 and .4, so if an admin sees this comment, I'm just helping to get the list down.

Affects me even after redownloading the snapshot version, and is getting worse, where I have to spam it like 40 times now instead of 15. It doesn't affect anyone else one my server, just me. I hope that they fix this soon.

Sorry, just added one.