Return to library activity when document activity is closed.
diff --git a/lib/src/main/java/com/artifex/mupdf/viewer/DocumentActivity.java b/lib/src/main/java/com/artifex/mupdf/viewer/DocumentActivity.java
index db94fa6..708b74c 100644
--- a/lib/src/main/java/com/artifex/mupdf/viewer/DocumentActivity.java
+++ b/lib/src/main/java/com/artifex/mupdf/viewer/DocumentActivity.java
@@ -810,7 +810,10 @@
 
 	@Override
 	public void onBackPressed() {
-		if (!mDocView.popHistory())
+		if (!mDocView.popHistory()) {
 			super.onBackPressed();
+			Intent intent = getPackageManager().getLaunchIntentForPackage(getComponentName().getPackageName());
+			startActivity(intent);
+		}
 	}
 }