Can you adjust a slide duration without dragging the end point?

Thanks again. I've read all the responses and watched all the videos.

Unfortunately, none of them contain a method to shorten the time line, except by manually dragging it.

Changing the duration of indidual objects only helps if you're trying to make the time line longer. 

Here is the challenge!

• Make a new side
• Create an object with a very long duration, eg. 900 seconds    (Right-click and use the 'timing' controls to do this)
• Delete the object
• Figure out a way to reduce the timeline back to 10 seconds without having to drag it manually.

And then, post the solution here for instant fame and glory.