In the Go To Web action, there is a new window properties section which allows you to set specific parameters for the popup window.
Can you please add a checkbox option under the
to open the window full screen?
I have an external activity that I built, and instead of using this canned action, I had to add a OnMclRunJS to run the following code:
var params = [
'fullscreen=yes' // only works in IE, but here for completeness
var popup = window.open('EN/index.html', 'popup_window', params);