Setting the height of a report

I am trying to set the height of a report, and position it in the center of the screen when it opens but I am having some difficulty. The two images attached show how it is currently displayed, and how I want it too be displayed (using the 'Sizable' property)

Hopefully you can help,

Thanks

Attached Images

	Issue.jpg (282.7 KB)
	Correct.jpg (278.8 KB)