Overlay API for Custom Visuals – allow pop-ups outside the iframe

[CristobalC]

When developing **custom visuals** we often need to display menus,
rich tooltips or dialogs that don’t fit inside the visual’s
rectangle. Today everything is rendered inside an `<iframe>` with
`overflow:hidden`, so content is clipped when the user resizes the
object.

We request an **Overlay / Popup API** that lets a custom visual
render content over the entire canvas, following the same UI
behavior as native visuals (slicer dropdown, calendar, etc.).

Minimum requirements:
1. Host method such as `displayOverlay(htmlElement, options)`.
2. Z-index managed by the host to avoid stacking conflicts.
3. Auto-close when clicking outside or switching pages.
4. Works in Desktop, Service and mobile.

Benefits:
* User experience identical to native visuals.
* Saves dashboard space.

* Enables advanced tooltips, in-place editors, wizards, etc.

Thank you for considering this feature – it would unlock many
scenarios for the custom-visual community.

[CristobalC]

@Microsoft

[kadirkkkk1]

I was just reporting a bug about this. Then search for the ideas and found this idea. Lets open this a bit more so people who suffer from this problem can find this idea and upvote. The biggest problem in this restriction is that we can not use any other dropdown slicer other than built-in one because slicer can not show values when height is small as selection part (1 row where written "All" when nothing is selected) @CristobalC can you please add a dropdown slicer screenshot from Inforiver Super filter for example so that authorities can understand what we suffer from.