diff --git a/ganttzk-demo-webapp/src/main/java/org/navalplanner/web/planner/DataForPlanner.java b/ganttzk-demo-webapp/src/main/java/org/navalplanner/web/planner/DataForPlanner.java
index 2a7dd7b4a..eceb30c1f 100644
--- a/ganttzk-demo-webapp/src/main/java/org/navalplanner/web/planner/DataForPlanner.java
+++ b/ganttzk-demo-webapp/src/main/java/org/navalplanner/web/planner/DataForPlanner.java
@@ -102,6 +102,11 @@ public class DataForPlanner {
                         return null;
                     }
 
+                    @Override
+                    public boolean isApplicableTo(ITaskFundamentalProperties task) {
+                        return true;
+                    }
+
                 });
         configuration.setDoubleClickCommand(new ICommandOnTask<ITaskFundamentalProperties>() {
 
@@ -123,6 +128,11 @@ public class DataForPlanner {
                         return null;
                     }
 
+                    @Override
+                    public boolean isApplicableTo(ITaskFundamentalProperties task) {
+                        return true;
+                    }
+
                 });
         return configuration;
     }
diff --git a/ganttzk/src/main/java/org/zkoss/ganttz/CommandOnTaskContextualized.java b/ganttzk/src/main/java/org/zkoss/ganttz/CommandOnTaskContextualized.java
index 37e0be5ae..8224691b9 100644
--- a/ganttzk/src/main/java/org/zkoss/ganttz/CommandOnTaskContextualized.java
+++ b/ganttzk/src/main/java/org/zkoss/ganttz/CommandOnTaskContextualized.java
@@ -93,7 +93,8 @@ public class CommandOnTaskContextualized<T> {
     }
 
     public boolean accepts(TaskComponent taskComponent) {
-        return true;
+        T domainObject = domainObjectFor(taskComponent.getTask());
+        return commandOnTask.isApplicableTo(domainObject);
     }
 
 }
diff --git a/ganttzk/src/main/java/org/zkoss/ganttz/adapters/PlannerConfiguration.java b/ganttzk/src/main/java/org/zkoss/ganttz/adapters/PlannerConfiguration.java
index 01780190c..6c6626fb8 100644
--- a/ganttzk/src/main/java/org/zkoss/ganttz/adapters/PlannerConfiguration.java
+++ b/ganttzk/src/main/java/org/zkoss/ganttz/adapters/PlannerConfiguration.java
@@ -73,6 +73,11 @@ public class PlannerConfiguration<T> implements IDisabilityConfiguration {
             return null;
         }
 
+        @Override
+        public boolean isApplicableTo(T task) {
+            return true;
+        }
+
     }
 
     private IAdapterToTaskFundamentalProperties<T> adapter;
diff --git a/ganttzk/src/main/java/org/zkoss/ganttz/extensions/ICommandOnTask.java b/ganttzk/src/main/java/org/zkoss/ganttz/extensions/ICommandOnTask.java
index dca265d71..0da5dcef2 100644
--- a/ganttzk/src/main/java/org/zkoss/ganttz/extensions/ICommandOnTask.java
+++ b/ganttzk/src/main/java/org/zkoss/ganttz/extensions/ICommandOnTask.java
@@ -28,4 +28,11 @@ public interface ICommandOnTask<T> {
 
     public void doAction(IContextWithPlannerTask<T> context, T task);
 
+    /**
+     * @param task
+     * @return <code>true</code> if and only if this command is applicable to
+     *         task
+     */
+    public boolean isApplicableTo(T task);
+
 }
diff --git a/navalplanner-webapp/src/main/java/org/navalplanner/web/planner/allocation/ResourceAllocationCommand.java b/navalplanner-webapp/src/main/java/org/navalplanner/web/planner/allocation/ResourceAllocationCommand.java
index 87d8e3419..db5bf6fa1 100644
--- a/navalplanner-webapp/src/main/java/org/navalplanner/web/planner/allocation/ResourceAllocationCommand.java
+++ b/navalplanner-webapp/src/main/java/org/navalplanner/web/planner/allocation/ResourceAllocationCommand.java
@@ -48,7 +48,7 @@ public class ResourceAllocationCommand implements IResourceAllocationCommand {
     @Override
     public void doAction(IContextWithPlannerTask<TaskElement> context,
             TaskElement task) {
-        if (task instanceof Task) {
+        if (isApplicableTo(task)) {
             this.resourceAllocationController.showWindow((Task) task, context
                     .getTask(), planningState);
         }
@@ -72,5 +72,9 @@ public class ResourceAllocationCommand implements IResourceAllocationCommand {
         return "/common/img/ico_allocation.png";
     }
 
+    @Override
+    public boolean isApplicableTo(TaskElement task) {
+        return task instanceof Task;
+    }
 
 }
diff --git a/navalplanner-webapp/src/main/java/org/navalplanner/web/planner/calendar/CalendarAllocationCommand.java b/navalplanner-webapp/src/main/java/org/navalplanner/web/planner/calendar/CalendarAllocationCommand.java
index 03f28fb40..06e83f700 100644
--- a/navalplanner-webapp/src/main/java/org/navalplanner/web/planner/calendar/CalendarAllocationCommand.java
+++ b/navalplanner-webapp/src/main/java/org/navalplanner/web/planner/calendar/CalendarAllocationCommand.java
@@ -46,7 +46,7 @@ public class CalendarAllocationCommand implements ICalendarAllocationCommand {
     @Override
     public void doAction(IContextWithPlannerTask<TaskElement> context,
             TaskElement task) {
-        if (task instanceof Task) {
+        if (isApplicableTo(task)) {
             this.calendarAllocationController.showWindow((Task) task, context
                     .getTask());
         }
@@ -68,4 +68,9 @@ public class CalendarAllocationCommand implements ICalendarAllocationCommand {
         return "/common/img/ico_calendar.png";
     }
 
+    @Override
+    public boolean isApplicableTo(TaskElement task) {
+        return task instanceof Task;
+    }
+
 }
diff --git a/navalplanner-webapp/src/main/java/org/navalplanner/web/planner/milestone/AddMilestoneCommand.java b/navalplanner-webapp/src/main/java/org/navalplanner/web/planner/milestone/AddMilestoneCommand.java
index d58c6fe56..3cf694e35 100644
--- a/navalplanner-webapp/src/main/java/org/navalplanner/web/planner/milestone/AddMilestoneCommand.java
+++ b/navalplanner-webapp/src/main/java/org/navalplanner/web/planner/milestone/AddMilestoneCommand.java
@@ -104,4 +104,9 @@ public class AddMilestoneCommand implements IAddMilestoneCommand {
         return "/common/img/milestone.png";
     }
 
+    @Override
+    public boolean isApplicableTo(TaskElement task) {
+        return true;
+    }
+
 }
\ No newline at end of file
diff --git a/navalplanner-webapp/src/main/java/org/navalplanner/web/planner/milestone/DeleteMilestoneCommand.java b/navalplanner-webapp/src/main/java/org/navalplanner/web/planner/milestone/DeleteMilestoneCommand.java
index 715748a28..4a45fef7a 100644
--- a/navalplanner-webapp/src/main/java/org/navalplanner/web/planner/milestone/DeleteMilestoneCommand.java
+++ b/navalplanner-webapp/src/main/java/org/navalplanner/web/planner/milestone/DeleteMilestoneCommand.java
@@ -42,7 +42,7 @@ public class DeleteMilestoneCommand implements IDeleteMilestoneCommand {
     @Override
     public void doAction(IContextWithPlannerTask<TaskElement> context,
             TaskElement task) {
-        if (task instanceof TaskMilestone) {
+        if (isApplicableTo(task)) {
             planningState.removed(task);
             context.remove(task);
         }
@@ -63,4 +63,9 @@ public class DeleteMilestoneCommand implements IDeleteMilestoneCommand {
         this.planningState = planningState;
     }
 
+    @Override
+    public boolean isApplicableTo(TaskElement task) {
+        return task instanceof TaskMilestone;
+    }
+
 }
diff --git a/navalplanner-webapp/src/main/java/org/navalplanner/web/planner/tabs/PlanningTabCreator.java b/navalplanner-webapp/src/main/java/org/navalplanner/web/planner/tabs/PlanningTabCreator.java
index eb2619ab2..6ee6fc221 100644
--- a/navalplanner-webapp/src/main/java/org/navalplanner/web/planner/tabs/PlanningTabCreator.java
+++ b/navalplanner-webapp/src/main/java/org/navalplanner/web/planner/tabs/PlanningTabCreator.java
@@ -119,6 +119,11 @@ public class PlanningTabCreator {
                     public String getIcon() {
                         return "/common/img/ico_planificador.png";
                     }
+
+                    @Override
+                    public boolean isApplicableTo(TaskElement task) {
+                        return true;
+                    }
                 };
                 commands.add(scheduleCommand);
                 companyPlanningController.setAdditional(commands);
diff --git a/navalplanner-webapp/src/main/java/org/navalplanner/web/planner/taskedition/EditTaskCommand.java b/navalplanner-webapp/src/main/java/org/navalplanner/web/planner/taskedition/EditTaskCommand.java
index 9fafd14c5..65cb24251 100644
--- a/navalplanner-webapp/src/main/java/org/navalplanner/web/planner/taskedition/EditTaskCommand.java
+++ b/navalplanner-webapp/src/main/java/org/navalplanner/web/planner/taskedition/EditTaskCommand.java
@@ -84,4 +84,9 @@ public class EditTaskCommand implements IEditTaskCommand {
         return "/common/img/ico_editar.png";
     }
 
+    @Override
+    public boolean isApplicableTo(TaskElement task) {
+        return true;
+    }
+
 }