diff --git a/src/FileModificationObserver.h b/src/FileModificationObserver.h
index 4e3ad53..463d0a1 100644
--- a/src/FileModificationObserver.h
+++ b/src/FileModificationObserver.h
@@ -4,7 +4,7 @@
 #include<vector>
 
 struct AFileModificationListener {
-	virtual bool OnTrigger() = 0;
+	virtual bool OnFileChanged(const std::string& filename) = 0;
 };
 
 struct FileModificationObserver {
@@ -26,6 +26,7 @@ struct FileModificationObserver {
 		if (iter == mObserverInfos.end()) {
 			FileObserverInfo observer_info;
 			observer_info.mListeners.push_back(listener);
+			UpdateFileInfo(filename, observer_info);
 			mObserverInfos[filename] = observer_info;
 		} else {
 			iter->second.mListeners.push_back(listener);
@@ -40,14 +41,14 @@ struct FileModificationObserver {
 
 		std::vector<AFileModificationListener*>::iterator listener_iter = iter->second.mListeners.begin();
 		while (listener_iter != iter->second.mListeners.end()) {
-			if ((*listener_iter)->OnTrigger())
+			if (!(*listener_iter)->OnFileChanged(filename))
 				break;
 
 			listener_iter++;
 		}
 	}
 
-	void CheckFileModification(const std::string& filename, FileObserverInfo& observer_info) {
+	bool UpdateFileInfo(const std::string& filename, FileObserverInfo& observer_info) {
 		struct stat attr;
 		bool stat_result = stat(filename.c_str(), &attr);
 
@@ -67,9 +68,15 @@ struct FileModificationObserver {
 			observer_info.mFileMTimeNSec = attr.st_mtim.tv_nsec;
 			observer_info.mFileSize = attr.st_size;
 
-			gLog ("Detected file change of %s: new size %d",
-					filename.c_str(), attr.st_size);
+			return true;
+		}
+		return false;
+	}
 
+	void CheckFileModification(const std::string& filename, FileObserverInfo& observer_info) {
+		if (UpdateFileInfo(filename, observer_info)) {
+			gLog ("Detected file change of %s: new size %d",
+					filename.c_str(), observer_info.mFileSize);
 			Trigger(filename);
 		}
 	}
diff --git a/src/Globals.h b/src/Globals.h
index d11d734..3e61165 100644
--- a/src/Globals.h
+++ b/src/Globals.h
@@ -3,9 +3,6 @@
 #include "math_types.h"
 #include "Utils.h"
 
-#define USE_DOCKS 1
-
-
 struct Timer;
 extern Timer* gTimer;
 
@@ -26,3 +23,6 @@ extern ReadSerializer* gReadSerializer;
 
 struct GuiInputState;
 extern GuiInputState* gGuiInputState;
+
+struct FileModificationObserver;
+extern FileModificationObserver* gFileModificationObserver;
diff --git a/src/main.cc b/src/main.cc
index ecf1f0c..c240e58 100644
--- a/src/main.cc
+++ b/src/main.cc
@@ -18,6 +18,7 @@
 #include "imgui_dock.h"
 #include "imgui_impl_glfw_gl3.h"
 
+#include "FileModificationObserver.h"
 #include "Serializer.h"
 
 Timer* gTimer = nullptr;
@@ -27,6 +28,7 @@ RuntimeModuleManager* gModuleManager = nullptr;
 WriteSerializer* gWriteSerializer = nullptr;
 ReadSerializer* gReadSerializer = nullptr;
 GuiInputState* gGuiInputState = nullptr;
+FileModificationObserver* gFileModificationObserver = nullptr;
 double gTimeAtStart = 0;
 
 double mouse_scroll_x = 0.;
@@ -143,6 +145,10 @@ int main(void)
 	ImGui_ImplGlfwGL3_Init(gWindow, true);
 	ImGui::LoadDock();
 
+	// FileModificationObserver
+	FileModificationObserver file_modification_observer;
+	gFileModificationObserver = &file_modification_observer;
+
 	// Timer
 	Timer timer;
 	gTimer = &timer;
@@ -227,6 +233,10 @@ int main(void)
 
 		usleep(16000);
 
+		if (glfwGetKey(gWindow, GLFW_KEY_F5) == GLFW_PRESS) {
+			gFileModificationObserver->Update();
+		} 
+
 		glfwSwapBuffers(gWindow);
 	}
 
diff --git a/src/modules/RenderModule.cc b/src/modules/RenderModule.cc
index ce490be..d7a6bb2 100644
--- a/src/modules/RenderModule.cc
+++ b/src/modules/RenderModule.cc
@@ -312,6 +312,7 @@ void Renderer::Initialize(int width, int height) {
 	// Simple Shader
 	mDefaultProgram = RenderProgram("data/shaders/vs_simple.glsl", "data/shaders/fs_simple.glsl");
 	bool load_result = mDefaultProgram.Load();
+	mDefaultProgram.RegisterFileModification();
 	assert(load_result);
 	muDefaultModelViewProjection = mDefaultProgram.GetUniformLocation("uModelViewProj");	
 	muDefaultColor = mDefaultProgram.GetUniformLocation("uColor");	
@@ -333,6 +334,7 @@ void Renderer::Initialize(int width, int height) {
 	// Program for color texture rendering
 	mRenderQuadProgramColor = RenderProgram("data/shaders/vs_passthrough.glsl", "data/shaders/fs_simpletexture.glsl");
 	load_result = mRenderQuadProgramColor.Load();
+	mRenderQuadProgramColor.RegisterFileModification();
 	assert(load_result);
 	muRenderQuadModelViewProj = mRenderQuadProgramColor.GetUniformLocation("uModelViewProj");
 		
@@ -342,6 +344,7 @@ void Renderer::Initialize(int width, int height) {
 	// Program for depth texture rendering
 	mRenderQuadProgramDepth = RenderProgram("data/shaders/vs_passthrough.glsl", "data/shaders/fs_depthbuffer.glsl");
 	load_result = mRenderQuadProgramDepth.Load();
+	mRenderQuadProgramDepth.RegisterFileModification();
 	assert(load_result);
 	muRenderQuadDepthModelViewProj = mRenderQuadProgramDepth.GetUniformLocation( "uModelViewProj");
 	muRenderQuadDepthNear = mRenderQuadProgramDepth.GetUniformLocation("uNear");	
diff --git a/src/modules/RenderUtils.cc b/src/modules/RenderUtils.cc
index 8df695b..e5d997f 100644
--- a/src/modules/RenderUtils.cc
+++ b/src/modules/RenderUtils.cc
@@ -7,6 +7,7 @@
 #include "RenderModule.h"
 #include "RenderUtils.h"
 #include "Globals.h"
+#include "FileModificationObserver.h"
 
 #define STB_IMAGE_IMPLEMENTATION
 
@@ -140,6 +141,16 @@ GLuint RenderProgram::GetUniformLocation(const std::string& name) {
 	return result;
 }
 
+void RenderProgram::RegisterFileModification() {
+	gFileModificationObserver->AddListener(mVertexShaderFilename, this);	
+	gFileModificationObserver->AddListener(mFragmentShaderFilename, this);	
+}
+
+bool RenderProgram::OnFileChanged(const std::string& filename) {
+	gLog("Renderprogram reload as file %s changed", filename.c_str());
+	return true;
+}
+
 //
 // RenderTarget
 //
diff --git a/src/modules/RenderUtils.h b/src/modules/RenderUtils.h
index d60449b..b139578 100644
--- a/src/modules/RenderUtils.h
+++ b/src/modules/RenderUtils.h
@@ -5,6 +5,8 @@
 
 #include <GL/gl3w.h>    // This example is using gl3w to access OpenGL functions (because it is small). You may use glew/glad/glLoadGen/etc. whatever already works for you.
 
+#include "FileModificationObserver.h"
+
 #include <vector>
 
 struct Transform {
@@ -127,7 +129,7 @@ struct Transform {
 	}
 };
 
-struct RenderProgram {
+struct RenderProgram : AFileModificationListener {
 	std::string mVertexShaderFilename;
 	std::string mFragmentShaderFilename;
 
@@ -146,6 +148,9 @@ struct RenderProgram {
 	~RenderProgram();
 
 	bool Load();
+
+	void RegisterFileModification();
+	virtual bool OnFileChanged(const std::string& filename);
 };
 
 struct RenderSettings;
@@ -244,8 +249,6 @@ struct VertexArray {
 			b(255),
 			a(255) {}
 
-
-
 		VertexData(
 				float x,
 				float y,