diff --git a/.project b/.project
index 018de1f..10f0f1d 100644
--- a/.project
+++ b/.project
@@ -14,4 +14,51 @@
 	<natures>
 		<nature>org.eclipse.m2e.core.maven2Nature</nature>
 	</natures>
+	<filteredResources>
+		<filter>
+			<id>1378848121085</id>
+			<name></name>
+			<type>30</type>
+			<matcher>
+				<id>org.eclipse.ui.ide.multiFilter</id>
+				<arguments>1.0-projectRelativePath-matches-false-false-x4o-driver</arguments>
+			</matcher>
+		</filter>
+		<filter>
+			<id>1378848121092</id>
+			<name></name>
+			<type>30</type>
+			<matcher>
+				<id>org.eclipse.ui.ide.multiFilter</id>
+				<arguments>1.0-projectRelativePath-matches-false-false-x4o-eld-doc</arguments>
+			</matcher>
+		</filter>
+		<filter>
+			<id>1378848121099</id>
+			<name></name>
+			<type>30</type>
+			<matcher>
+				<id>org.eclipse.ui.ide.multiFilter</id>
+				<arguments>1.0-projectRelativePath-matches-false-false-x4o-html</arguments>
+			</matcher>
+		</filter>
+		<filter>
+			<id>1378848121142</id>
+			<name></name>
+			<type>30</type>
+			<matcher>
+				<id>org.eclipse.ui.ide.multiFilter</id>
+				<arguments>1.0-projectRelativePath-matches-false-false-x4o-meta</arguments>
+			</matcher>
+		</filter>
+		<filter>
+			<id>1378848121146</id>
+			<name></name>
+			<type>30</type>
+			<matcher>
+				<id>org.eclipse.ui.ide.multiFilter</id>
+				<arguments>1.0-projectRelativePath-matches-false-false-x4o-tool</arguments>
+			</matcher>
+		</filter>
+	</filteredResources>
 </projectDescription>
diff --git a/pom.xml b/pom.xml
index 04da51c..806f208 100644
--- a/pom.xml
+++ b/pom.xml
@@ -79,6 +79,7 @@
     <maven-changelog-plugin.version>2.2</maven-changelog-plugin.version>
     <maven-jar-plugin.version>2.4</maven-jar-plugin.version>
     <maven-license-plugin.version>1.10.b1</maven-license-plugin.version>
+    <maven-clean-plugin.version>2.4.1</maven-clean-plugin.version>
     
     <!-- Build non-maven plugin versions -->
     <webstart-maven-plugin.version>1.0-beta-1</webstart-maven-plugin.version>
@@ -112,6 +113,31 @@
   </properties>
   <build>
     <plugins>
+      <plugin>
+        <artifactId>maven-clean-plugin</artifactId>
+        <version>${maven-clean-plugin.version}</version>
+        <executions>
+          <execution>
+            <id>default-clean</id>
+            <phase>clean</phase>
+            <goals>
+              <goal>clean</goal>
+            </goals>
+            <configuration>
+              <!-- only clean childeren of target not folder itself. -->
+              <excludeDefaultDirectories>true</excludeDefaultDirectories>
+              <filesets>
+                <fileset>
+                  <directory>${project.build.directory}</directory>
+                  <includes>
+                    <include>**/*</include>
+                  </includes>
+                </fileset>
+              </filesets>
+            </configuration>
+          </execution>
+        </executions>
+      </plugin>
       <plugin>
         <groupId>org.apache.maven.plugins</groupId>
         <artifactId>maven-compiler-plugin</artifactId>
diff --git a/x4o-tool/.project b/x4o-tool/.project
index 9ae0cb0..ccf9be7 100644
--- a/x4o-tool/.project
+++ b/x4o-tool/.project
@@ -14,4 +14,24 @@
 	<natures>
 		<nature>org.eclipse.m2e.core.maven2Nature</nature>
 	</natures>
+	<filteredResources>
+		<filter>
+			<id>1378240259439</id>
+			<name></name>
+			<type>30</type>
+			<matcher>
+				<id>org.eclipse.ui.ide.multiFilter</id>
+				<arguments>1.0-projectRelativePath-matches-false-false-x4o-tool-ant-plugin</arguments>
+			</matcher>
+		</filter>
+		<filter>
+			<id>1378240259445</id>
+			<name></name>
+			<type>30</type>
+			<matcher>
+				<id>org.eclipse.ui.ide.multiFilter</id>
+				<arguments>1.0-projectRelativePath-matches-false-false-x4o-tool-maven-plugin</arguments>
+			</matcher>
+		</filter>
+	</filteredResources>
 </projectDescription>