This might seem like a strange question. Is there some sort of way for an app to launched by pressing the screen for a few seconds on touch screen phones? the reason why I ask is because this would be a great feature for like a panic button. of course the app will have to calibrate to the owner's thumb to prevent accidental pressing from objects in purse or pockets.
Regards.
As far as I know this isn't really possible. But there are apps available in the Play Store that implement a Panic Button where you can place a button on your home screen (and maybe also your lock screen, but I haven't it yet).
One of those apps I found is Red Panic Button. But you can also have a look in the Play Store yourself if you search for something like Panic Button etc.
There are several shutdown apps on the market, they all needed root. You can combine them with WidgetLocker and put their icons on your lockscreen for quick shutdown.
