When you long press the homoe button and select an app from the recent apps, this app comes to the foreground the way you left it, in the same activity. How can someone launch an app simulating this behavior ? Something like this.. :
if (there is a stack for this app in system memory): restore it
else : launch it the usual way.
Just to make it clear i'm talking about launching an OTHER app from withing MY app. And of course i am reffering to the apps whose previous state exists in the OS memory at the given momment.