This is not a feature
Lion (Mac OS 10.7) introduced a device that comes in handy when you use an iPad or iPhone: a way to produce accented letters without having to use three key-combinations: simply hold down the base-letter long enough for all the alternatives to appear and then pick the one needed.
I am on a real computer and I simply hate this feature. Whenever I finished typing a sentence I find that many vowals will simply have have removed from it. Apparently, if you simply go on typing at a more or less high speed, the device thinks you want none of the alternatives… Below you find a picture of the thing.
Since I am writing a book in LaTeX, which has no use for accented letters, and at a reasonably high typing-speed, you understand my frustration.
Just now I grabbed all my anger and started off to the internet for the umpteenth time to find a solution, again to no avail. But a remark got stuck in my head: that the feature pops up when you hold down the relevant letter.
So I checked my keyboard settings in System Preferences, and found I had specified the Delay Until Repeat as “short”—I changed it to long, and bingo. I hope this helps all of you who are as frustrated as I have been for the last few weeks.