Workaround for nullpointer bug in support lib, close #591

OpenKeychain/src/main/java/android/support/v4/widget/FixedDrawerLayout.java

@@ -0,0 +1,33 @@
+package android.support.v4.widget;
+
+import android.content.Context;
+import android.util.AttributeSet;
+import android.view.Gravity;
+import android.view.View;
+
+/**
+ * Fix for NullPointerException at android.support.v4.widget.DrawerLayout.isContentView(DrawerLayout.java:840)
+ * <p/>
+ * http://stackoverflow.com/a/18107942
+ */
+public class FixedDrawerLayout extends DrawerLayout {
+    public FixedDrawerLayout(Context context) {
+        super(context);
+    }
+
+    public FixedDrawerLayout(Context context, AttributeSet attrs) {
+        super(context, attrs);
+    }
+
+    public FixedDrawerLayout(Context context, AttributeSet attrs, int defStyle) {
+        super(context, attrs, defStyle);
+    }
+
+    @Override
+    boolean isContentView(View child) {
+        if (child == null) {
+            return false;
+        }
+        return ((LayoutParams) child.getLayoutParams()).gravity == Gravity.NO_GRAVITY;
+    }
+}