refresh i window from another

[io]

i have my browser in witch i have developped a toolbar (extesion):
1- when i push over a button of this toolbar a new window is opened
2- in this second window there is a button

i would like that, when i push the button (point 2), the page loaded
in the browser (for exemple my homepage) will refresh....
the problem is that when i do the reload of the main page is load the
page blank....
how can i do it???