Seeing that thread by Obama#2 reminded me that some of you may not know how to get your tools perfectly aligned so i went ahead and made this for you.
First you have your button on your app like this:
Next you go here to center the form horizontally and Vertically:
And now it is perfectly centered! and i drew lines to show its in the center just like the other thing.
Hope I helped :]
Also you have to click on the object to fet the Format to show