When you press a button, a collapse happens. It goes away when you click the button again. It's not quite the same as a drop-down list where you have a button and then alternatives that come down from the button. This will cause something that wasn't there before to show up on the screen.

 

 

Design a Collapse/Expand Feature

 

 

Render Collapse/Expand on screen

• Collapse
  • 
• Expand
  •