Click a button -> open a link in a new tab?

I’m making a 2D game with C# for the webplayer. When a user clic on a “share” button, I want twitter to open in a new tab of the browser.

I tried this, but this doesn’t seem to work with current browsers:

void OnMouseUpAsButton() {      
    Application.ExternalEval("'', '_blank')");

So how can I make this work? Thanks!

Try this: