Check settings.

AH-HA! In Advanced Settings, I didn't even See that hiding there!

Thank you Very much!

A Long habit of immediately moving the mouse to the Top of a tab with a single mouse gesture and then Click to change to that selected tab is Incredibly frustrating and may Completely put me off using Opera.

It May seem minor but when its a Very old Very set habit - and it's not one I should have to break.