diff --git a/src/gui/bg_window.cpp b/src/gui/bg_window.cpp
new file mode 100644
index 0000000..cee674d
--- /dev/null
+++ b/src/gui/bg_window.cpp
@@ -0,0 +1,36 @@
+#include "gui_internal.hpp"
+
+void draw_bg_window(){
+    const ImGuiDockNodeFlags dockspace_flags =
+            ImGuiDockNodeFlags_PassthruCentralNode;
+    const ImGuiWindowFlags window_flags =
+        ImGuiWindowFlags_MenuBar |
+        ImGuiWindowFlags_NoDocking |
+        ImGuiWindowFlags_NoScrollbar |
+        ImGuiWindowFlags_NoScrollWithMouse |
+        ImGuiWindowFlags_NoBringToFrontOnFocus |
+        ImGuiWindowFlags_NoFocusOnAppearing |
+        ImGuiWindowFlags_NoMove |
+        ImGuiWindowFlags_NoResize |
+        ImGuiWindowFlags_NoCollapse |
+        ImGuiWindowFlags_NoTitleBar |
+        ImGuiWindowFlags_NoBackground;
+    // not dockable window that always bound to viewport
+    ImGuiViewport* viewport = ImGui::GetWindowViewport();
+    ImGui::SetNextWindowPos(viewport->Pos, ImGuiCond_Always);
+    ImGui::SetNextWindowSize(viewport->Size, ImGuiCond_Always);
+    ImGui::PushStyleVar(ImGuiStyleVar_WindowRounding, 0.0f);
+    ImGui::PushStyleVar(ImGuiStyleVar_WindowBorderSize, 0.0f);
+	ImGui::PushStyleVar(ImGuiStyleVar_WindowPadding, ImVec2(0.0f, 0.0f));
+    ImGui::Begin("bg_window", nullptr, window_flags);
+    ImGui::PopStyleVar(3);
+
+    // DockSpace
+    ImGuiID dockspace_id = ImGui::GetID("bg_dockspace");
+    ImGui::DockSpace(dockspace_id, ImVec2(0.0f, 0.0f), dockspace_flags);
+    
+    // MenuBar
+    //TODO
+
+    ImGui::End();
+}
diff --git a/src/gui/demo_ui.cpp b/src/gui/demo_ui.cpp
index 5b95393..a6100a1 100644
--- a/src/gui/demo_ui.cpp
+++ b/src/gui/demo_ui.cpp
@@ -1,14 +1,15 @@
 #include "gui_internal.hpp"
 
 bool show_demo_window = true;
-bool show_another_window = false;
+bool show_metrics_window = true;
 
-Maybe demo_ui_draw(ImGuiIO& io){
-    // 1. Show the big demo window (Most of the sample code is in ImGui::ShowDemoWindow()! You can browse its code to learn more about Dear ImGui!).
+void draw_demo_windows(ImGuiIO& io){
     if (show_demo_window)
         ImGui::ShowDemoWindow(&show_demo_window);
 
-    // 2. Show a simple window that we create ourselves. We use a Begin/End pair to create a named window.
+    if (show_metrics_window)
+        ImGui::ShowMetricsWindow(&show_metrics_window);
+
     {
         static float f = 0.0f;
         static int counter = 0;
@@ -17,7 +18,7 @@ Maybe demo_ui_draw(ImGuiIO& io){
 
         ImGui::Text("This is some useful text.");               // Display some text (you can use a format strings too)
         ImGui::Checkbox("Demo Window", &show_demo_window);      // Edit bools storing our window open/close state
-        ImGui::Checkbox("Another Window", &show_another_window);
+        ImGui::Checkbox("Metrics/Debug Window", &show_metrics_window);
 
         ImGui::SliderFloat("float", &f, 0.0f, 1.0f);            // Edit 1 float using a slider from 0.0f to 1.0f
         ImGui::ColorEdit3("clear color", (float*)&clear_color); // Edit 3 floats representing a color
@@ -30,16 +31,4 @@ Maybe demo_ui_draw(ImGuiIO& io){
         ImGui::Text("Application average %.3f ms/frame (%.1f FPS)", 1000.0f / io.Framerate, io.Framerate);
         ImGui::End();
     }
-
-    // 3. Show another simple window.
-    if (show_another_window)
-    {
-        ImGui::Begin("Another Window", &show_another_window);   // Pass a pointer to our bool variable (the window will have a closing button that will clear the bool when clicked)
-        ImGui::Text("Hello from another window!");
-        if (ImGui::Button("Close Me"))
-            show_another_window = false;
-        ImGui::End();
-    }
-
-    return MaybeNull;
 }
diff --git a/src/gui/gui_internal.hpp b/src/gui/gui_internal.hpp
index d2fdc50..41c06a1 100644
--- a/src/gui/gui_internal.hpp
+++ b/src/gui/gui_internal.hpp
@@ -12,4 +12,5 @@ extern ImVec4 clear_color; // background color for main window
 
 /// @brief frees all allocated resources
 void main_window_destroy();
-Maybe demo_ui_draw(ImGuiIO&);
+void draw_demo_windows(ImGuiIO&);
+void draw_bg_window();
diff --git a/src/gui/main_window.cpp b/src/gui/main_window.cpp
index 9ca4cc1..b286b49 100644
--- a/src/gui/main_window.cpp
+++ b/src/gui/main_window.cpp
@@ -46,10 +46,10 @@ Maybe main_window_open(const char* window_title){
     io.ConfigFlags |= ImGuiConfigFlags_NavEnableKeyboard;   // Enable Keyboard Controls   
     io.ConfigFlags |= ImGuiConfigFlags_NavEnableGamepad;    // Enable Gamepad Controls
     io.ConfigFlags |= ImGuiConfigFlags_DockingEnable;       // Enable Docking
-    io.ConfigFlags |= ImGuiConfigFlags_ViewportsEnable;     // Enable Multi-Viewport / Platform Windows
+    // io.ConfigFlags |= ImGuiConfigFlags_ViewportsEnable;     // Enable Multi-Viewport / Platform Windows
     io.ConfigDockingTransparentPayload = true;
     io.ConfigInputTextCursorBlink = false;
-    io.ConfigViewportsNoTaskBarIcon = true;
+    // io.ConfigViewportsNoTaskBarIcon = true;
     io.ConfigWindowsMoveFromTitleBarOnly = true;
 
     // Setup Dear ImGui style
@@ -113,7 +113,8 @@ Maybe draw_frame(){
     ImGuiIO& io = ImGui::GetIO();
 
     // Draw UI
-    try_cpp(demo_ui_draw(io), _5218, ;);
+    draw_bg_window();
+    draw_demo_windows(io);
 
     // Rendering
     ImGui::Render();