[TYPO3-english] Page Link to External URL does not accept _blank setting in 6.1.8

[Tony Lush]

On a site based on the bootstrap demo using TYPO3 6.1.8, the pages of 
type "Link to External URL" do not go to a new window or tab when the 
Link Target is set to _blank.

External links elsewhere on the site (not in a menu) fall under 
config.extTarget = _blank, and function properly

Any suggestions?

Thank you -- Tony