The Built-In/Control drawer contains blocks that, yes, control or act on events.
Take the first block if test then do—it's logic of response is simple but powerful. If a condition is true then do this; if it's not true, ignore. So, in the example here, the variable okay_to_press is true.
 |
Pressing the following button tells us it was okay. If it wasn't, nothing would have happened.
 |
The next five blocks—ifelse, choose, foreach, for range, and while—offer more sophisticated ways of controlling events and responses in our apps. We'll be using those a lot and will go into detail on their operation several times.
But, let's knock off another basic programming concept, loops: A loop goes round and round until something happens and is one of the basic tools in any programming language. In App Inventor, the while block is quite nice for doing loops. Here's how: follow along on your computer.