E-mail address gray in LO Calc

He, I have added an E-mail address in the field. Than I saw color: gray. Normal is the hyperlink a color: blue. How can I change?

I use LO Calc 4.4.2.2 release on Ubuntu MATE 15.04

[edit: added lo4 + ubuntu15 tags]

Please check this url Hyperlink Background Color in Spreadsheets .