diff --git a/src/Engine/Network/NetworkManager.cpp b/src/Engine/Network/NetworkManager.cpp
index 1768f22..738cb98 100644
--- a/src/Engine/Network/NetworkManager.cpp
+++ b/src/Engine/Network/NetworkManager.cpp
@@ -15,7 +15,19 @@ enzo::nt::OpId enzo::nt::NetworkManager::addOperator(op::OpInfo opInfo)
 {
 
     maxOpId_++;
-    gopStore_.emplace(maxOpId_, std::make_unique<GeometryOperator>(maxOpId_, opInfo));
+    std::unique_ptr<GeometryOperator> newOp = std::make_unique<GeometryOperator>(maxOpId_, opInfo);
+    newOp->nodeDirtied.connect(
+        [this](nt::OpId opId)
+        {
+            cookOp(opId);
+
+            if(getDisplayOp()==opId)
+            {
+                enzo::nt::GeometryOperator& displayOp = getGeoOperator(opId);
+                updateDisplay(displayOp.getOutputGeo(0));
+            }
+        });
+    gopStore_.emplace(maxOpId_, std::move(newOp));
     std::cout << "adding operator " << maxOpId_ << "\n";
 
     return maxOpId_;
@@ -51,27 +63,25 @@ bool enzo::nt::NetworkManager::isValidOp(nt::OpId opId)
 
 void enzo::nt::NetworkManager::setDisplayOp(OpId opId)
 {
-    std::cout << "gop size before: " << gopStore_.size() <<"\n";
     displayOp_=opId;
-    std::vector<enzo::nt::OpId> dependencyGraph = getDependencyGraph(opId);
-    enzo::geo::Geometry prevGeometry;
-    std::cout << "size: " << dependencyGraph.size() << "\n";
+    
+    cookOp(opId);
 
-    for(enzo::nt::OpId dependencyOpId : dependencyGraph)
-    {
-        cookOp(dependencyOpId);
-    }
-    std::cout << "gop size middle: " << gopStore_.size() <<"\n"; // <- size: 1
     enzo::nt::GeometryOperator& displayOp = getGeoOperator(opId);
     updateDisplay(displayOp.getOutputGeo(0));
-    std::cout << "gop size after: " << gopStore_.size() <<"\n";
+    displayNodeChanged();
 }
 
 void enzo::nt::NetworkManager::cookOp(enzo::nt::OpId opId)
 {
-    enzo::nt::GeometryOperator& op = getGeoOperator(opId);
-    enzo::op::Context context(opId, enzo::nt::nm());
-    op.cookOp(context);
+    std::vector<enzo::nt::OpId> dependencyGraph = getDependencyGraph(opId);
+
+    for(enzo::nt::OpId dependencyOpId : dependencyGraph)
+    {
+        enzo::nt::GeometryOperator& op = getGeoOperator(dependencyOpId);
+        enzo::op::Context context(dependencyOpId, enzo::nt::nm());
+        op.cookOp(context);
+    }
 }
 
 std::vector<enzo::nt::OpId> enzo::nt::NetworkManager::getDependencyGraph(enzo::nt::OpId opId)
diff --git a/src/Engine/Network/NetworkManager.h b/src/Engine/Network/NetworkManager.h
index a5a9f3d..87a6043 100644
--- a/src/Engine/Network/NetworkManager.h
+++ b/src/Engine/Network/NetworkManager.h
@@ -24,6 +24,8 @@ public:
     GeometryOperator& getGeoOperator(nt::OpId opId);
     void setDisplayOp(OpId opId);
 
+    boost::signals2::signal<void ()> displayNodeChanged;
+
     #ifdef UNIT_TEST
         void _reset();
     #endif
@@ -42,6 +44,8 @@ private:
     enzo::nt::OpId maxOpId_=0;
     // operator selected for displaying in the viewport
     std::optional<OpId> displayOp_=std::nullopt;
+
+
 Q_SIGNALS:
     void updateDisplay(enzo::geo::Geometry& geometry);
 
diff --git a/src/Engine/Operator/GeometryOperator.cpp b/src/Engine/Operator/GeometryOperator.cpp
index 93c0189..f66ee81 100644
--- a/src/Engine/Operator/GeometryOperator.cpp
+++ b/src/Engine/Operator/GeometryOperator.cpp
@@ -41,16 +41,24 @@ void nt::GeometryOperator::initParameters()
     {
         std::cout << "name: " << t->getName() << "\n";
         // create parameter
-        parameters_.push_back(
-            std::make_shared<prm::Parameter>(*t)
-        );
+        auto parameter = std::make_shared<prm::Parameter>(*t);
+        parameter->valueChanged.connect(boost::bind(&GeometryOperator::dirtyNode, this));
+
+        parameters_.push_back(parameter);
     }
 
 }
 
+void enzo::nt::GeometryOperator::dirtyNode()
+{
+    dirty_=true;
+    nodeDirtied(opId_);
+}
+
 void enzo::nt::GeometryOperator::cookOp(op::Context context)
 {
     opDef_->cookOp(context);
+    dirty_=false;
 }
 
 geo::Geometry& enzo::nt::GeometryOperator::getOutputGeo(unsigned outputIndex)
diff --git a/src/Engine/Operator/GeometryOperator.h b/src/Engine/Operator/GeometryOperator.h
index e4a0513..827114f 100644
--- a/src/Engine/Operator/GeometryOperator.h
+++ b/src/Engine/Operator/GeometryOperator.h
@@ -29,10 +29,16 @@ public:
     std::vector<std::weak_ptr<prm::Parameter>> getParameters();
     std::weak_ptr<prm::Parameter> getParameter(std::string parameterName);
 
+    void dirtyNode();
+
 
     unsigned int getMaxInputs() const;
     unsigned int getMaxOutputs() const;
 
+    // signals
+    boost::signals2::signal<void (nt::OpId)> nodeDirtied;
+
+
 
 private:
     void initParameters();
@@ -46,5 +52,6 @@ private:
     std::unique_ptr<enzo::nt::GeometryOpDef> opDef_;
     enzo::nt::OpId opId_;
     enzo::op::OpInfo opInfo_;
+    bool dirty_ = true;
 };
 }
diff --git a/src/Engine/Parameter/Parameter.cpp b/src/Engine/Parameter/Parameter.cpp
index 4f22343..bbe193e 100644
--- a/src/Engine/Parameter/Parameter.cpp
+++ b/src/Engine/Parameter/Parameter.cpp
@@ -1,7 +1,6 @@
 #include "Engine/Parameter/Parameter.h"
 #include <iostream>
 
-
 enzo::prm::Parameter::Parameter(Template prmTemplate)
 : template_{prmTemplate}
 {
@@ -21,5 +20,6 @@ enzo::bt::floatT enzo::prm::Parameter::evalFloat() const
 void enzo::prm::Parameter::setFloat(bt::floatT value)
 {
     floatValue_ = value;
+    valueChanged();
 }
 
diff --git a/src/Engine/Parameter/Parameter.h b/src/Engine/Parameter/Parameter.h
index e2ce818..dbf9cba 100644
--- a/src/Engine/Parameter/Parameter.h
+++ b/src/Engine/Parameter/Parameter.h
@@ -1,6 +1,7 @@
 #pragma once
 #include "Engine/Parameter/Template.h"
 #include "Engine/Types.h"
+#include <boost/signals2.hpp>
 
 namespace enzo::prm
 {
@@ -11,6 +12,7 @@ public:
     std::string getName() const;
     bt::floatT evalFloat() const;
     void setFloat(bt::floatT value);
+    boost::signals2::signal<void ()> valueChanged;
 private:
     Template template_;
     bt::floatT floatValue_ = 0;
diff --git a/src/Gui/Interface.cpp b/src/Gui/Interface.cpp
index ffd80cf..9a6a1bf 100644
--- a/src/Gui/Interface.cpp
+++ b/src/Gui/Interface.cpp
@@ -55,7 +55,8 @@ EnzoUI::EnzoUI()
 
     // connect signals
     connect(&enzo::nt::nm(), &enzo::nt::NetworkManager::updateDisplay, viewport, &Viewport::geometryChanged);
-    connect(&enzo::nt::nm(), &enzo::nt::NetworkManager::updateDisplay, parametersPanel, &ParametersPanel::selectionChanged);
+    enzo::nt::nm().displayNodeChanged.connect([parametersPanel](){parametersPanel->selectionChanged();});
+    // connect(&enzo::nt::nm(), &enzo::nt::NetworkManager::updateDisplay, parametersPanel, &ParametersPanel::selectionChanged);
 
 //  ─── end of EnzoUI ctor ───
 QTimer::singleShot(0, this, [=] {