TIP: If something goes out of view and you can't drag it back into view. Do one of these things..

[ameliacarrie]

JUST A TIP - Sometimes when you are editing text sizes or accidentally drag text off the editable screen, you just see the clear boxes and your text is hidden.  Use one of the below methods.
1. You can use align- Align to Center
2.  "drag" the clear box to the center. It will make the text so squished it will be letter over letter and long enough you'll be able to drag it back into view. 
3. Use the "+" symbol in the tools area. Once the text is big enough to see a part of it, then drag it back into view and make it smaller. 

[PenguinPower]

You can also use the alignment button to center the item and it will pop back into your workspace.

[ameliacarrie]

Thanks Penguin Power - I will add that.

[shellifitz]

Good tip Amelia.

I also use the keyboard shortcut alt+s after selecting the layer I want and it will snap to the center.  

[ibelieveimages]

Or the arrow keys on your keyboard

[ameliacarrie]

Thanks Shelifits and ibelieveimages.  I'll add your "tricks".  Whoops.... it won't let me edit the original post anymore. But, hopefully people will see your great ideas.

[NigelSutherland]

Maybe you can "select all", then scale down with the "minus" button: - until the missing bit shows. Deselect all. Move the rogue bit closer to the other elements. Select all, then increase in size again with the "plus" button so the remaining elements are back to previous size and position.

[NigelSutherland]

The vertically centre, under alignment, idea is a good one.