[Suggestion] provide an children builder

[iulian0512]

A children builder function that is invoked on speed dial click would allow a custom number of children that depends on the current application state.
For example the speed dial is used to add 3 categories of items into a list, but in some cases only 2 categories of items are possible to be added that's where the builder function comes in handy, it is invoked and based on some conditions it returns 2 children.

[prateekmedia]

Contributions are welcome, the package is only receives security-updates for now.