<GridLayout
        android:id="@+id/tracker_control_modal"
        xmlns:android="http://schemas.android.com/apk/res/android"
        xmlns:tools="http://schemas.android.com/tools"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:background="@color/master_blue_dark_transparent"
        android:columnCount="1"
        android:rowCount="1"
        >

    <LinearLayout
            android:id="@+id/tracker_control_root"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:orientation="vertical"
            android:background="@color/master_white"
            android:layout_column="0"
            android:layout_row="0"
            android:layout_gravity="center">

        <GridLayout
                style="@style/Style_TrackerControl_Item"
                android:id="@+id/tracker_control_item_preference">

            <Button
                    android:layout_width="match_parent"
                    android:layout_height="wrap_content"
                    android:text="close"
                    android:id="@+id/close_button"/>
        </GridLayout>


    </LinearLayout>

</GridLayout>

android:alpha="0.5" // - 50%
android:alpha="1" // - 100% (непрозрачный)

textView.getBackground().setAlpha(80);