Background overlay

[WieFel]

Hi,

thanks for this cool library. I really like it and it is very customizable!

However, one feature I am missing: a background overlay when the FAB is in active state.
Can that be added somehow?

[Robbendebiene]

Hi, I agree that it would be a good fit for the package.

I'm thinking of an overlayBuilder or backdropBuilder parameter:

Widget overlayBuilder(BuildContext context, bool isActive, VoidCallback toggle)

This way one should be able to

• add a colored box as the overlay
• add a gesture detector to hide the overlay on tap
• animate the overlay based on the isActive value

Unfortunatly I currently don't have enough time to add this, but PR is welcome :)

It could probably simply be added here with another check like

if (widget.overlayBuilder != null) overlayBuilder(overlayContext, isActive, toggle),