the RVR android bible was developed in 2009, more than 10 years ago, the tech stack has change a lot:(

Im trying to update the app to more modern androidx jetpack Material Components

Buttons in button bars should be borderless; use style="?android:attr/buttonBarButtonStyle" (and ?android:attr/buttonBarStyle on the layout parent)

Button bars typically use a borderless style for the buttons. Set the style="?android:attr/buttonBarButtonStyle" attribute on each of the buttons, and set style="?android:attr/buttonBarStyle" on the parent layout

Issue id: ButtonStyle

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