What problem does this feature solve?

We now use visibility: hiddenopacity: 0 to hide tooltip ( for fade-in-out animation I guess ). However, because DOM with visibility: hidden still affects layout, the invisible tooltip DOM results in a large empty space, which is problematic.

What does the proposed API look like?

When a tooltip is invisible, the DOM element is useless, we can safely remove it to save memory, or at least we can use display: none to prevent it from affecting layout. However it's harder ( but possible ) to apply fade-in-out animation when it's removed from DOM tree, we can add option tooltip: { animation: 'none' } to remove the fading animation