Open drop down button programatically

[bdlukaa]

Is your feature request related to a problem? Please describe.
Currently, there is no way to open a dropdown button programatically.

Describe the solution you'd like
Exposing DropDownButtonState, and use a key to open it

final dropdownKey = GlobalKey<DropDownButtonState>();

DropDownButton(
  key: dropdownKey,
  ...
);

to open the flyout:

dropdownKey.open();
dropdownKey.isOpen;
dropdownKey.close()

Describe alternatives you've considered
n/a

Additional context
#718

[tonka3000]

@bdlukaa Thanks for the PR. Works great. The only thing I am missing is the referenced close method from your example above. Do I miss something?

I'm using 4.4.0

This is my example:

final dropdownKey = GlobalKey<DropDownButtonState>();

// ....
ShowActionsMenuIntent:
      CallbackAction<ShowActionsMenuIntent>(onInvoke: (intent) {
    if (dropdownKey.currentState != null) {
      var isOpen = dropdownKey.currentState?.isOpen ?? false;
      if (!isOpen) {
        dropdownKey.currentState!.open();
      }
      else {
         dropdownKey.currentState!.close(); // <= no close available
       }
    }
  }),

[bdlukaa]

@tonka3000 sorry, it was a mistake by my part. There is no .close() to close the flyout. To close it, use Navigator.of(context).pop() or, if you provide a navigator key, use navigatroKey.pop()