Scrollbars autohide, select fix for reselecting current item closing popup

[gagnus]

Objective / Solution

• Select control didn't close when reselecting the current item (mouse or keyboard), because that doesn't send an event from underlying widget (list). Added a new event ReselectListRow to bevy_ui_widget and send that, picked it up in select to close the select.
• Scrollbar was hugging the right side of the popup too much so added some padding on it.
• Scrollbar was visible whether content fitted or not. Added an auto_hide (default to true).

Solution

cargo run --example feathers_gallery --features bevy_feathers

---

Showcase

Select where all items fit:

Select where they don't:

[viridia]

I would suggest adding a clarifying note here, as this makes certain assumptions about the layout structure of the parent container - those assumptions are true in the case of feathers, but may not be true for non-feathers widgets generally.

For example, a headless scrollbar can be placed in a grid, a flexbox, or it can float on top as a separate layer. For a floating scrollbar, altering the padding of the parent wouldn't be the right move.

Also, the above code appears to handle both horizontal and vertical scrollbars, but I would think that adjusting the right padding would only work for vertical scrollbars.

[gagnus]

good spot, thanks. will add comment to make clear ScrollbarGutter is just for padding based ones and fix horizontal.

[gagnus]

both scrollbars

reclaim horizontal (the bug)

reclaim vertical (existing working)