gtk properties can only have one argument using attributes

[etrombly]

Not sure if there is an easy fix to this, but I was trying to set the policy on a scrolled window. It requires the policy for the horizontal and vertical scrollbar, but you can only pass one argument.

gtk::ScrolledWindow {
    policy: (gtk::PolicyType::Never, gtk::PolicyType::Automatic),

edit: realized afterwords there is a separate vscrollbar and hscrollbar policy, but this might still be relevant for other properties.