The platform’s main thread. Plugin code runs here.
    For more information, see the UIKit documentation for iOS,
    or the MainThread documentation for Android.
    This thread is not shown in the performance overlay.

The UI thread executes Dart code in the Dart VM.
    This thread includes code that you wrote, and code executed by
    Flutter’s framework on your app’s behalf.
    When your app creates and displays a scene, the UI thread creates
    a layer tree, a lightweight object containing device-agnostic
    painting commands, and sends the layer tree to the raster thread to
    be rendered on the device. Don’t block this thread!
    Shown in the bottom row of the performance overlay.