I was assisting a Tibetan user with an issue typing Sanskrit stacks today. We were both reading the documentation for the keyboard and both running into the same problem -- we just could not get the stacks to form. We were both running in Vista so I knew that the problem was not rendering.
We both tried to type pad<space><space>+ma<space>, which according to the documentation, as we read it, should give us པདྨ but was instead giving us པད+མ་.
So I did a little research. I took the source file for the keyboard and searched for a couple of the stacked characters -- in this case, I searched for the Unicode character Tibetan subjoined ma (U+0FA8). As soon as I found it in the source, I understood the problem. The source line read:
"+m" + " " > U+0FA8
We needed to type just +m, not +ma.
Now when I go back to the documentation and read it again, it seems obvious enough. But it clearly isn't, because three different people have read the same instructions and made the same mistake.
Now I have a new item on my list: clarify the stacking instructions in the Tibetan EWTS keyboard!