Requested functionality for iced apps.

[Anikmoujegy]

Move back button to header bar when back button is not visible on the page anymore. Because it is annoying to scroll up then go back in large pages. Else you can add a floating button on the page to go to top at once like many websites are offering this functionality.

[wiiznokes]

I noticed that on cosmic- settings. I think the back button should be in the header bar

[mmstick]

This is app-specific

[mmstick]

Any requests to change visual design requires approval from @pop-os/ux

[maria-komarova]

Design prototypes include making the part with back button and page header sticky on scroll but it hasn't been implemented yet and I'm not sure on the timeline for this. We've considered moving the back button to a header but decided against it for various reasons including window resizing to a narrow width.

[mmstick]

Then I'll make issues for decoupling the scrollable in libcosmic's application trait, and then making page headers static.

[maria-komarova]

Thanks @mmstick