diff --git a/source/gui/GUIbase.h b/source/gui/GUIbase.h
index a380cd8f26..75a9a3f1da 100644
--- a/source/gui/GUIbase.h
+++ b/source/gui/GUIbase.h
@@ -209,6 +209,11 @@ public:
 	 *			will be unchanged.
 	 */
 	bool SetClientArea(const CStr& Value);
+
+	bool operator==(const CClientArea& other) const
+	{
+		return pixel == other.pixel && percent == other.percent;
+	}
 };
 
 //--------------------------------------------------------
diff --git a/source/gui/tests/test_ParseString.h b/source/gui/tests/test_ParseString.h
new file mode 100644
index 0000000000..dbea409981
--- /dev/null
+++ b/source/gui/tests/test_ParseString.h
@@ -0,0 +1,43 @@
+/* Copyright (C) 2013 Wildfire Games.
+ * This file is part of 0 A.D.
+ *
+ * 0 A.D. is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * 0 A.D. is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with 0 A.D.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#include "lib/self_test.h"
+
+#include "gui/GUIbase.h"
+
+class TestGuiParseString : public CxxTest::TestSuite 
+{
+public:
+	void test_clientarea()
+	{
+		CClientArea ca;
+		TS_ASSERT(ca.SetClientArea("0 1 2 3"));
+		TS_ASSERT_EQUALS(ca, CClientArea(CRect(0, 1, 2, 3), CRect(0, 0, 0, 0)));
+
+		TS_ASSERT(ca.SetClientArea("5% 10%+1 20%-2 3"));
+		TS_ASSERT_EQUALS(ca, CClientArea(CRect(0, 1, -2, 3), CRect(5, 10, 20, 0)));
+
+		TS_ASSERT(!ca.SetClientArea("0+5% 1 2 3"));
+
+		TS_ASSERT(!ca.SetClientArea("5%+10-10 1 2 3"));
+
+		TS_ASSERT(ca.SetClientArea("5% 10%-1 -20%-2 3"));
+		TS_ASSERT_EQUALS(ca, CClientArea(CRect(0, -1, -2, 3), CRect(5, 10, -20, 0)));
+
+		TS_ASSERT(!ca.SetClientArea("5% 10%+1 -20%-2 3")); // parser bug
+	}
+};