app/internal/window: [Android] disable platform focus highlight

Gio apps use a single Android View for the entire UI, rendering the platform
focus highlight unsuitable.

Signed-off-by: Elias Naur <mail@eliasnaur.com>

app/internal/window/GioView.java

@@ -60,6 +60,9 @@ public final class GioView extends SurfaceView implements Choreographer.FrameCal
 		if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.O) {
 			scrollXScale = conf.getScaledHorizontalScrollFactor();
 			scrollYScale = conf.getScaledVerticalScrollFactor();
+
+			// The platform focus highlight is not aware of Gio's widgets.
+			setDefaultFocusHighlightEnabled(false);
 		} else {
 			float listItemHeight = 48; // dp
 			float px = TypedValue.applyDimension(