Documentation for ScrolledWindow::new misleading

[donaldcallen]

"Usually you want to pass None for the adjustments, which will cause the scrolled window to create them for you."

Pass 'None' for the adjustments leads to

error[E0283]: type annotations required: cannot resolve _: gtk::IsA<gtk::Adjustment>
--> src/main.rs:159:42
|
159 | let scrolled_window:ScrolledWindow = ScrolledWindow::new(None, None);
| ^^^^^^^^^^^^^^^^^^^
|
= note: required by gtk::ScrolledWindow::new

You have gtk::NONE_ADJUSTMENT defined. Why not mention that in the documentation instead of 'None' and avoid leading users down this incorrect path?

[17cupsofcoffee]

Relevant thread on URLO where we dug into this error: https://users.rust-lang.org/t/do-not-understand-this-error/30924/

[sdroege]

You can also pass None::<&gtk::Adjustment> FWIW. These problems exist because functions can't declare default types for generic parameters yet.