I’d like to start the very first blog post with the mysterious button which bugged me for a while.
I saw this “DHB” button in the elevator of the hotel beside my office. 
I was curious and asked my friends around but nobody knows what it means. (We’re in BEIJING and we speak Chinese…)
So I took a picture with my iPhone, and forgot about it later.
1 month ago, I went to the hotel for my wedding again, and the button showed up again. This time I asked the girl behind the reception desk and she told me this button is for emergency.
“OK, so nobody hits it?” I said.
“No.”
I believe nobody hits it but I don’t think it’s for alert.
So I googled it and found out yes it stands for “Door Hold Button”..
Then my points are:
1. In China, people hit the “Open” button to hold the door
2. Chinese people really don’t know what “DHB” means
3. The DHB button is really placed very well among other buttons that it looks neat
4. Nobody hits it
So the lesson learnt is – Don’t put any DHB button in your software.