diff --git a/src/main/java/org/gcube/portlets/widgets/dataminermanagerwidget/client/experiments/OperatorCategoryPanel.java b/src/main/java/org/gcube/portlets/widgets/dataminermanagerwidget/client/experiments/OperatorCategoryPanel.java
index c23268c..16432fe 100644
--- a/src/main/java/org/gcube/portlets/widgets/dataminermanagerwidget/client/experiments/OperatorCategoryPanel.java
+++ b/src/main/java/org/gcube/portlets/widgets/dataminermanagerwidget/client/experiments/OperatorCategoryPanel.java
@@ -105,21 +105,8 @@ public class OperatorCategoryPanel extends SimpleContainer {
 	 * @return
 	 */
 	private String getTooltipTemplate(String base, String id, boolean hasImage, String description){ 
-		String image;
-		if(hasImage==false||id==null||id.isEmpty()){
-        	image=DataMinerManagerPanel.resources.categoryDefaultImage().getSafeUri().asString();
-        }  else {
-        	switch(id){
-        	case "DISTRIBUTIONS":
-        		image=DataMinerManagerPanel.resources.categoryDefaultImage().getSafeUri().asString();
-        		break;
-        	default:
-        		image=DataMinerManagerPanel.resources.categoryDefaultImage().getSafeUri().asString();
-        		break;
-        			
-        	}
-        }
-		
+		String image=DataMinerManagerPanel.resources.categoryDefaultImage().getSafeUri().asString();
+				
 		String html =  
 			"<div class='categoryItemTooltip'>"+
 				"<img src='"+image+ "' >"+
diff --git a/src/main/java/org/gcube/portlets/widgets/dataminermanagerwidget/client/experiments/OperatorPanel.java b/src/main/java/org/gcube/portlets/widgets/dataminermanagerwidget/client/experiments/OperatorPanel.java
index 534508b..550c8a0 100644
--- a/src/main/java/org/gcube/portlets/widgets/dataminermanagerwidget/client/experiments/OperatorPanel.java
+++ b/src/main/java/org/gcube/portlets/widgets/dataminermanagerwidget/client/experiments/OperatorPanel.java
@@ -113,21 +113,7 @@ public class OperatorPanel extends SimpleContainer {
 	 */
 	private String getTooltipTemplate(String base, String id, boolean hasImage,
 			String description) {
-		String image;
-		if(hasImage==false||id==null||id.isEmpty()){
-        	image=DataMinerManagerPanel.resources.operatorsDefaultImage().getSafeUri().asString();
-        }  else {
-        	switch(id){
-        	case "AquamapsNative2050":
-        		image=DataMinerManagerPanel.resources.operatorsAquamapsNative2050Operator().getSafeUri().asString();
-        		break;
-        	default:
-        		image=DataMinerManagerPanel.resources.operatorsDefaultImage().getSafeUri().asString();
-        		break;
-        			
-        	}
-        }
-		
+		String image=DataMinerManagerPanel.resources.operatorsDefaultImage().getSafeUri().asString();
 		
 		String template = "<div class='categoryItemTooltip'>" + "<img src='"
 				+ image +"' >" + Format.ellipse(description, TOOLTIP_DESCRIPTION_LENGHT)
diff --git a/src/main/java/org/gcube/portlets/widgets/dataminermanagerwidget/client/resources/DataMiner.css b/src/main/java/org/gcube/portlets/widgets/dataminermanagerwidget/client/resources/DataMiner.css
index 068b6b6..cc58fbd 100644
--- a/src/main/java/org/gcube/portlets/widgets/dataminermanagerwidget/client/resources/DataMiner.css
+++ b/src/main/java/org/gcube/portlets/widgets/dataminermanagerwidget/client/resources/DataMiner.css
@@ -107,7 +107,7 @@
 	cursor: pointer;
 }
 
-.categoryItem {
+@sprite .categoryItem {
 	margin-top: 10px;
 	margin-left: 5px;
 	font-size: 15px;
@@ -115,17 +115,22 @@
 	font-weight: bolder;
 	border-bottom: 2px solid #505050;
 	margin-bottom: 5px;
-	background-image: url(images/triangle-right.png);
+	gwt-image: "triangleRight";
+	/*background-image: url(images/triangle-right.png);*/
 	background-repeat: no-repeat;
 	background-position: right;
 }
 
-.categoryItem-Collapsed {
-	background-image: url(images/triangle-right.png);
+
+
+@sprite .categoryItem-Collapsed {
+	gwt-image: "triangleRight";
+	/*"background-image: url(images/triangle-right.png);*/
 }
 
-.categoryItem-Expanded {
-	background-image: url(images/triangle-down.png);
+@sprite .categoryItem-Expanded {
+	gwt-image: triangleDown";
+	/*"background-image: url(images/triangle-down.png);*/
 }
 
 .categoryItem:hover {
@@ -300,9 +305,11 @@
 	background-color: gray;
 }
 
-.workflow-parameters-preload {
+@sprite .workflow-parameters-preload {
 	display: block;
-	background: url('ajax-loader-big.gif') no-repeat;
+	gwt-image: "loaderBig";
+	background-repeat: no-repeat;
+	/*background: url('ajax-loader-big.gif') no-repeat;*/
 	width: 400px;
 	height: 180px;
 }
diff --git a/src/main/resources/org/gcube/portlets/widgets/dataminermanagerwidget/client/resources/DataMiner.css b/src/main/resources/org/gcube/portlets/widgets/dataminermanagerwidget/client/resources/DataMiner.css
index 068b6b6..cc58fbd 100644
--- a/src/main/resources/org/gcube/portlets/widgets/dataminermanagerwidget/client/resources/DataMiner.css
+++ b/src/main/resources/org/gcube/portlets/widgets/dataminermanagerwidget/client/resources/DataMiner.css
@@ -107,7 +107,7 @@
 	cursor: pointer;
 }
 
-.categoryItem {
+@sprite .categoryItem {
 	margin-top: 10px;
 	margin-left: 5px;
 	font-size: 15px;
@@ -115,17 +115,22 @@
 	font-weight: bolder;
 	border-bottom: 2px solid #505050;
 	margin-bottom: 5px;
-	background-image: url(images/triangle-right.png);
+	gwt-image: "triangleRight";
+	/*background-image: url(images/triangle-right.png);*/
 	background-repeat: no-repeat;
 	background-position: right;
 }
 
-.categoryItem-Collapsed {
-	background-image: url(images/triangle-right.png);
+
+
+@sprite .categoryItem-Collapsed {
+	gwt-image: "triangleRight";
+	/*"background-image: url(images/triangle-right.png);*/
 }
 
-.categoryItem-Expanded {
-	background-image: url(images/triangle-down.png);
+@sprite .categoryItem-Expanded {
+	gwt-image: triangleDown";
+	/*"background-image: url(images/triangle-down.png);*/
 }
 
 .categoryItem:hover {
@@ -300,9 +305,11 @@
 	background-color: gray;
 }
 
-.workflow-parameters-preload {
+@sprite .workflow-parameters-preload {
 	display: block;
-	background: url('ajax-loader-big.gif') no-repeat;
+	gwt-image: "loaderBig";
+	background-repeat: no-repeat;
+	/*background: url('ajax-loader-big.gif') no-repeat;*/
 	width: 400px;
 	height: 180px;
 }