Extension - Top Bar

I have an idea for an extension, in android studio there is a nice top bar, is there someone who can make an extension to have this?

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are you talking about the action bar?

https://developer.android.com/training/appbar/index.html

this is currently not possible as extension, see the App InventorExtensions document

Note:  One limitation of the current extension component implementation is that it creates non-visible components only (i.e., components that do not show on the designer screen).   MITplans to remove this restriction in future versions of the extension component system

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