Open hyperlink window not working in FireFox like it does in IE

I have created some hyperlinks in some of my blank pages and selected the "Display in a new window" and left the "(Default browser controls as default size)" as it is by default.

Now when I click on the link on the the Internet using Internet Explorer, the hyperlinked pages opens in a new window and is the default size (whatever that is as set by default). In other words it works just as expected.

Now when I click on the same hyperlink using FireFox, it opens a new window all right but opens it full screen.

Any ideas why this is happening in FireFox and not IE or any ideas how I can resolve this?

Thanks