Viewport and window sizes in the tooltip are not accurate when viewing a site at increased magnification

My screen resolution is 1066 x 768 but it is not one of the pc's mentioned here so I used the tablet of the same resolution. Now the screen pic is slightly oversized , off-center but with clearance at the top. What can I do?

Resize all open windows to a single preset

New update notification

does not work offline

Works beautifully for me!

Tooltip doesn't show in Chrome 27