Alternative to GetButtonUp for GUI.Button

I need a system where I click an hold a GUI button, something charges, and when i let go of the button, do something else? There doesn’t seem to be a simple piece of code in the reference for such a basic problem. It’s ridiculous.
If you can get ButtonDown and ButtonUp for physical keys, why not for the GUI?

A hint, this is for android.

How about this?

   var buttonDown : boolean;

   function OnGUI()
   {
          if(GUILayout.Button("Press Me"))
          {
              buttonDown = true;
              DoSomething();
          }
          else if(buttonDown)
          {
               buttonDown = false;
               DoSomethingElse();
          }
   }