WordPress/src/main/res/layout/media_gallery_picker_layout.xml

<?xml version="1.0" encoding="utf-8"?>
<GridView xmlns:android="http://schemas.android.com/apk/res/android"
          android:id="@+id/media_gallery_picker_gridview"
          android:layout_width="match_parent"
          android:layout_height="match_parent"
          android:scrollbarStyle="outsideOverlay"
          android:stretchMode="columnWidth"
          android:paddingLeft="@dimen/margin_small"
          android:paddingRight="@dimen/margin_small"
          android:verticalSpacing="@dimen/margin_small"
          android:horizontalSpacing="@dimen/margin_small"
          android:numColumns="@integer/media_grid_num_columns"/>