diff --git a/src/tests/kits/interface/InterfaceKitTestAddon.cpp b/src/tests/kits/interface/InterfaceKitTestAddon.cpp
index 39d376ef6d..a792d5b278 100644
--- a/src/tests/kits/interface/InterfaceKitTestAddon.cpp
+++ b/src/tests/kits/interface/InterfaceKitTestAddon.cpp
@@ -6,6 +6,7 @@
 #include "bdeskbar/DeskbarTest.h"
 #include "bpolygon/PolygonTest.h"
 #include "bregion/RegionTest.h"
+#include "bwidthbuffer/WidthBufferTest.h"
 
 BTestSuite* getTestSuite() {
 	BTestSuite *suite = new BTestSuite("Interface");
@@ -15,6 +16,7 @@ BTestSuite* getTestSuite() {
 	suite->addTest("BDeskbar", DeskbarTestSuite());
 	suite->addTest("BPolygon", PolygonTestSuite());
 	suite->addTest("BRegion", RegionTestSuite());
+	suite->addTest("_BWidthBuffer_", WidthBufferTestSuite());
 	
 	return suite;
 }
diff --git a/src/tests/kits/interface/Jamfile b/src/tests/kits/interface/Jamfile
index 669a7baac1..3f33893fc9 100644
--- a/src/tests/kits/interface/Jamfile
+++ b/src/tests/kits/interface/Jamfile
@@ -1,10 +1,13 @@
 SubDir OBOS_TOP src tests kits interface ;
 
+UsePrivateHeaders interface ;
+
 # Let Jam know where to find some of our source files
 SEARCH_SOURCE += [ FDirName $(SUBDIR) bbitmap ] ;
 SEARCH_SOURCE += [ FDirName $(SUBDIR) bdeskbar ] ;
 SEARCH_SOURCE += [ FDirName $(SUBDIR) bpolygon ] ;
 SEARCH_SOURCE += [ FDirName $(SUBDIR) bregion ] ;
+SEARCH_SOURCE += [ FDirName $(SUBDIR) bwidthbuffer ] ;
 
 SEARCH_SOURCE += [ FDirName $(TOP) src kits interface ] ;
 
@@ -37,6 +40,10 @@ CommonTestLib libinterfacetest.so
 		RegionIntersect.cpp
 		RegionOffsetBy.cpp
 
+		#_BWidthBuffer_
+		WidthBufferTest.cpp
+		WidthBufferSimpleTest.cpp
+
 	: <boot!home!config!lib>libopenbeos.so
 		be stdc++.r4
 	: be stdc++.r4
diff --git a/src/tests/kits/interface/bwidthbuffer/WidthBufferSimpleTest.cpp b/src/tests/kits/interface/bwidthbuffer/WidthBufferSimpleTest.cpp
new file mode 100644
index 0000000000..b545714511
--- /dev/null
+++ b/src/tests/kits/interface/bwidthbuffer/WidthBufferSimpleTest.cpp
@@ -0,0 +1,82 @@
+#include "WidthBufferSimpleTest.h"
+#include "cppunit/TestCaller.h"
+
+#include <Application.h>
+#include <Font.h>
+
+#include <stdio.h>
+
+// Needed because it isn't available in beos headers
+double round(float n)
+{	
+	int32 tmp = (int32)floor(n + 0.5);
+	return (double)tmp;
+}
+
+
+WidthBufferSimpleTest::WidthBufferSimpleTest(std::string name) :
+		BTestCase(name)
+{
+	fWidthBuffer = new _BWidthBuffer_;
+}
+
+ 
+
+WidthBufferSimpleTest::~WidthBufferSimpleTest()
+{
+	delete fWidthBuffer;
+}
+
+
+void 
+WidthBufferSimpleTest::PerformTest(void)
+{
+	const char *str = "Something";
+	const char *str2 = "Some Text";
+	const char *longString = "ABCDEFGHIJKLMNOPQRSTUVYXWZ abcdefghijklmnopqrstuvwyxz";
+	
+	// Some charachters which takes more than one byte
+	const char *str3 = "30u8g 2342 42nfrç°S£^GF°W§|£^?£ç$£!1ààà'ì";
+	
+	const BFont *font = be_plain_font;
+	
+	// We use round() here because the width returned by
+	// _BWidthBuffer_::StringWidth() isn't _exactly_ the same
+	// as the one returned by BFont::StringWidth();
+	float width = fWidthBuffer->StringWidth(str, 0, strlen(str), font);
+	CPPUNIT_ASSERT(round(width) == font->StringWidth(str)); 
+	
+	width = fWidthBuffer->StringWidth(str2, 0, strlen(str2), font);
+	CPPUNIT_ASSERT(round(width) == font->StringWidth(str2));
+	
+	width = fWidthBuffer->StringWidth(longString, 0, strlen(longString), font);
+	CPPUNIT_ASSERT(round(width) == font->StringWidth(longString));
+	
+	// pass the first string again, it should be completely cached
+	// in _BWidthBuffer_'s hash table
+	width = fWidthBuffer->StringWidth(str, 0, strlen(str), font);
+	CPPUNIT_ASSERT(round(width) == font->StringWidth(str)); 
+	
+	width = fWidthBuffer->StringWidth(str3, 0, strlen(str3), font);
+	CPPUNIT_ASSERT(round(width) == font->StringWidth(str3)); 
+	
+	// choose a different font and ask the same strings as before
+	font = be_fixed_font;
+	width = fWidthBuffer->StringWidth(longString, 0, strlen(longString), font);
+	CPPUNIT_ASSERT(round(width) == font->StringWidth(longString));
+	
+	width = fWidthBuffer->StringWidth(str, 0, strlen(str), font);
+	CPPUNIT_ASSERT(round(width) == font->StringWidth(str)); 
+	
+	width = fWidthBuffer->StringWidth(str2, 0, strlen(str2), font);
+	CPPUNIT_ASSERT(round(width) == font->StringWidth(str2));
+}
+
+
+CppUnit::Test *WidthBufferSimpleTest::suite(void)
+{	
+	typedef CppUnit::TestCaller<WidthBufferSimpleTest>
+		WidthBufferSimpleTestCaller;
+		
+	return(new WidthBufferSimpleTestCaller("_BWidthBuffer_::Simple Test", &WidthBufferSimpleTest::PerformTest));
+}
diff --git a/src/tests/kits/interface/bwidthbuffer/WidthBufferSimpleTest.h b/src/tests/kits/interface/bwidthbuffer/WidthBufferSimpleTest.h
new file mode 100644
index 0000000000..14337faa9d
--- /dev/null
+++ b/src/tests/kits/interface/bwidthbuffer/WidthBufferSimpleTest.h
@@ -0,0 +1,19 @@
+#ifndef __WidthBufferSIMPLETest_H
+#define __WidthBufferSIMPLETest_H
+
+#include "TestCase.h"
+#include <WidthBuffer.h>
+
+class WidthBufferSimpleTest : public BTestCase
+{
+public:
+	static Test *suite(void);
+	void PerformTest(void);
+	WidthBufferSimpleTest(std::string name = "");
+	virtual ~WidthBufferSimpleTest();
+
+private:
+	_BWidthBuffer_ *fWidthBuffer;
+};
+	
+#endif
diff --git a/src/tests/kits/interface/bwidthbuffer/WidthBufferTest.cpp b/src/tests/kits/interface/bwidthbuffer/WidthBufferTest.cpp
new file mode 100644
index 0000000000..65a3b901e3
--- /dev/null
+++ b/src/tests/kits/interface/bwidthbuffer/WidthBufferTest.cpp
@@ -0,0 +1,14 @@
+#include "cppunit/Test.h"
+#include "cppunit/TestSuite.h"
+#include "WidthBufferTest.h"
+#include "WidthBufferSimpleTest.h"
+
+
+CppUnit::Test *WidthBufferTestSuite()
+{
+	CppUnit::TestSuite *testSuite = new CppUnit::TestSuite();
+	
+	testSuite->addTest(WidthBufferSimpleTest::suite());	
+	
+	return testSuite;
+}
diff --git a/src/tests/kits/interface/bwidthbuffer/WidthBufferTest.h b/src/tests/kits/interface/bwidthbuffer/WidthBufferTest.h
new file mode 100644
index 0000000000..6954d8f3e4
--- /dev/null
+++ b/src/tests/kits/interface/bwidthbuffer/WidthBufferTest.h
@@ -0,0 +1,8 @@
+#ifndef __WIDTHBUFFER_TEST_H
+#define __WIDTHBUFFER_TEST_H
+
+class CppUnit::Test;
+
+CppUnit::Test *WidthBufferTestSuite();
+
+#endif	__WIDTHBUFFER_TEST_H