[Feature]: priority-overflow - Weaken assumption that menu is only visible w/ 1+ overflow items

Library

React Components / v9 (@fluentui/react-components)

Describe the feature that you would like added

I've been working the overflow components today, and for our particular use case, we have a desire to have the overflow menu also be visible when there aren't only overflown elements.

The current logic in OverflowManager explicitly checks whether there are any overflown items in order to decide whether to consider the size of the menu: https://github.com/microsoft/fluentui/blob/master/packages/react-components/priority-overflow/src/overflowManager.ts#L87-L103 This means that if we don't have the equivalent of return null (see the example OverflowMenu components in the docs, the sizing logic is incorrect).

From my own quick experiment, changing this line:

const overflowMenuSize = invisibleItemQueue.size() > 0 && overflowMenu ? getOffsetSize(overflowMenu) : 0;

to:

const overflowMenuSize = overflowMenu ? getOffsetSize(overflowMenu) : 0;

My first instinct was to try and find a way to override this default behaviour, but it seems non-trivial. So now I'm wondering whether it'd be better as a configurable option of the overflow itself.

Have you discussed this feature with our team

No response

Additional context

No response

Validations

• Check that there isn't already an issue that request the same feature to avoid creating a duplicate.

Priority

None

Start in packages/react-components/priority-overflow/src/overflowManager.ts at the overflow menu sizing logic described in the issue. Verify the behavior when an overflow menu exists with no overflown items, then determine whether the requested behavior should be the default or a configurable option; done means the menu is sized correctly in that case and the relevant priority-overflow behavior is covered.