Bug#885343: Close icon on Preferences dialog not centred on hover

[Jason Crain]

On Tue, Dec 26, 2017 at 01:56:35PM +0000, Phil Wyett wrote:
> Close icon on Preferences dialog not centred on hover. See attached 
> screenshot.

 Looks like the dialog is a little too tall.  What is the pixel size of
 your screen?