diff --git a/src/app/editor/overworld/overworld_editor.cc b/src/app/editor/overworld/overworld_editor.cc
index 68c52dd6..273be4d4 100644
--- a/src/app/editor/overworld/overworld_editor.cc
+++ b/src/app/editor/overworld/overworld_editor.cc
@@ -141,7 +141,7 @@ void OverworldEditor::Initialize() {
     HOVER_HINT("Gfx Group Editor");
   });
   gui::AddTableColumn(toolset_table_, "##sep3", ICON_MD_MORE_VERT);
-  gui::AddTableColumn(toolset_table_, "##Properties", [&]() {
+  gui::AddTableColumn(toolset_table_, "##CopyMap", [&]() {
     if (Button(ICON_MD_CONTENT_COPY)) {
       std::vector<uint8_t> png_data;
       png_data = maps_bmp_[current_map_].GetPngData();
@@ -161,6 +161,24 @@ void OverworldEditor::Initialize() {
   gui::AddTableColumn(toolset_table_, "##Properties", [&]() {
     Checkbox("Properties", &show_properties_editor_);
   });
+  gui::AddTableColumn(toolset_table_, "##MapLock", [&]() {
+    if (Button(current_map_lock_ ? ICON_MD_LOCK : ICON_MD_LOCK_OPEN)) {
+      current_map_lock_ = !current_map_lock_;
+    }
+    HOVER_HINT(current_map_lock_ ? "Unlock Map" : "Lock Map");
+  });
+  gui::AddTableColumn(toolset_table_, "##CustomBG", [&]() {
+    if (Button(ICON_MD_PALETTE)) {
+      show_custom_bg_color_editor_ = !show_custom_bg_color_editor_;
+    }
+    HOVER_HINT("Custom Background Colors");
+  });
+  gui::AddTableColumn(toolset_table_, "##Overlay", [&]() {
+    if (Button(ICON_MD_LAYERS)) {
+      show_overlay_editor_ = !show_overlay_editor_;
+    }
+    HOVER_HINT("Overlay Editor");
+  });
 }
 
 absl::Status OverworldEditor::Load() {
@@ -220,6 +238,18 @@ void OverworldEditor::DrawToolset() {
     ImGui::End();
   }
 
+  if (show_custom_bg_color_editor_) {
+    ImGui::Begin("Custom Background Colors", &show_custom_bg_color_editor_);
+    DrawCustomBackgroundColorEditor();
+    ImGui::End();
+  }
+
+  if (show_overlay_editor_) {
+    ImGui::Begin("Overlay Editor", &show_overlay_editor_);
+    DrawOverlayEditor();
+    ImGui::End();
+  }
+
   // TODO: Customizable shortcuts for the Overworld Editor
   if (!ImGui::IsAnyItemActive()) {
     using enum EditingMode;
@@ -423,6 +453,40 @@ void OverworldEditor::DrawCustomOverworldMapSettings() {
         ImGui::EndTable();
       }
     }
+    
+    // Add additional v3 features
+    if (asm_version >= 3 && asm_version != 0xFF) {
+      Separator();
+      Text("ZSCustomOverworld v3 Features:");
+      
+      // Main Palette
+      if (gui::InputHexByte("Main Palette",
+                            overworld_.mutable_overworld_map(current_map_)
+                                ->mutable_main_palette(),
+                            kInputFieldSize)) {
+        RefreshMapProperties();
+        status_ = RefreshMapPalette();
+        RefreshOverworldMap();
+      }
+      
+      // Animated GFX
+      if (gui::InputHexByte("Animated GFX",
+                            overworld_.mutable_overworld_map(current_map_)
+                                ->mutable_animated_gfx(),
+                            kInputFieldSize)) {
+        RefreshMapProperties();
+        RefreshOverworldMap();
+      }
+      
+      // Subscreen Overlay
+      if (gui::InputHexWord("Subscreen Overlay",
+                            overworld_.mutable_overworld_map(current_map_)
+                                ->mutable_subscreen_overlay(),
+                            kInputFieldSize + 20)) {
+        RefreshMapProperties();
+        RefreshOverworldMap();
+      }
+    }
 
     ImGui::EndTable();
   }
@@ -783,6 +847,8 @@ void OverworldEditor::DrawOverworldCanvas() {
     ow_map_canvas_.DrawContextMenu();
   } else {
     ow_map_canvas_.set_draggable(false);
+    // Always show our custom overworld context menu
+    DrawOverworldContextMenu();
   }
 
   if (overworld_.is_loaded()) {
@@ -1340,6 +1406,227 @@ absl::Status OverworldEditor::RefreshTile16Blockset() {
   return absl::OkStatus();
 }
 
+void OverworldEditor::DrawCustomBackgroundColorEditor() {
+  static uint8_t asm_version = (*rom_)[zelda3::OverworldCustomASMHasBeenApplied];
+  
+  if (asm_version < 2 || asm_version == 0xFF) {
+    Text("Custom background colors are only available in ZSCustomOverworld v2+");
+    return;
+  }
+  
+  // Check if area-specific background colors are enabled
+  bool bg_enabled = (*rom_)[zelda3::OverworldCustomAreaSpecificBGEnabled] != 0x00;
+  if (Checkbox("Enable Area-Specific Background Colors", &bg_enabled)) {
+    (*rom_)[zelda3::OverworldCustomAreaSpecificBGEnabled] = bg_enabled ? 0x01 : 0x00;
+  }
+  
+  if (!bg_enabled) {
+    Text("Area-specific background colors are disabled.");
+    return;
+  }
+  
+  Separator();
+  
+  // Display current map's background color
+  Text("Current Map: %d (0x%02X)", current_map_, current_map_);
+  
+  // Get current background color
+  uint16_t current_bg_color = (*rom_)[zelda3::OverworldCustomAreaSpecificBGPalette + (current_map_ * 2)] |
+                              ((*rom_)[zelda3::OverworldCustomAreaSpecificBGPalette + (current_map_ * 2) + 1] << 8);
+  
+  // Convert SNES color to ImVec4
+  ImVec4 current_color = ImVec4(
+    ((current_bg_color & 0x1F) * 8) / 255.0f,
+    (((current_bg_color >> 5) & 0x1F) * 8) / 255.0f,
+    (((current_bg_color >> 10) & 0x1F) * 8) / 255.0f,
+    1.0f
+  );
+  
+  // Color picker
+  if (ColorPicker4("Background Color", (float*)&current_color, 
+                   ImGuiColorEditFlags_NoAlpha | ImGuiColorEditFlags_InputRGB)) {
+    // Convert ImVec4 back to SNES color
+    uint16_t new_color = 
+      (static_cast<uint16_t>(current_color.x * 31) & 0x1F) |
+      ((static_cast<uint16_t>(current_color.y * 31) & 0x1F) << 5) |
+      ((static_cast<uint16_t>(current_color.z * 31) & 0x1F) << 10);
+    
+    // Write to ROM
+    (*rom_)[zelda3::OverworldCustomAreaSpecificBGPalette + (current_map_ * 2)] = new_color & 0xFF;
+    (*rom_)[zelda3::OverworldCustomAreaSpecificBGPalette + (current_map_ * 2) + 1] = (new_color >> 8) & 0xFF;
+    
+    // Update the overworld map
+    overworld_.mutable_overworld_map(current_map_)->set_area_specific_bg_color(new_color);
+    
+    // Refresh the map
+    RefreshOverworldMap();
+  }
+  
+  Separator();
+  
+  // Show color preview
+  Text("Color Preview:");
+  ImGui::ColorButton("##bg_preview", current_color, ImGuiColorEditFlags_NoTooltip, ImVec2(100, 50));
+  
+  SameLine();
+  Text("SNES Color: 0x%04X", current_bg_color);
+}
+
+void OverworldEditor::DrawOverlayEditor() {
+  static uint8_t asm_version = (*rom_)[zelda3::OverworldCustomASMHasBeenApplied];
+  
+  if (asm_version < 1 || asm_version == 0xFF) {
+    Text("Overlay editor is only available in ZSCustomOverworld v1+");
+    return;
+  }
+  
+  // Check if subscreen overlays are enabled
+  bool overlay_enabled = (*rom_)[zelda3::OverworldCustomSubscreenOverlayEnabled] != 0x00;
+  if (Checkbox("Enable Subscreen Overlays", &overlay_enabled)) {
+    (*rom_)[zelda3::OverworldCustomSubscreenOverlayEnabled] = overlay_enabled ? 0x01 : 0x00;
+  }
+  
+  if (!overlay_enabled) {
+    Text("Subscreen overlays are disabled.");
+    return;
+  }
+  
+  Separator();
+  
+  // Display current map's overlay
+  Text("Current Map: %d (0x%02X)", current_map_, current_map_);
+  
+  // Get current overlay ID
+  uint16_t current_overlay = (*rom_)[zelda3::OverworldCustomSubscreenOverlayArray + (current_map_ * 2)] |
+                             ((*rom_)[zelda3::OverworldCustomSubscreenOverlayArray + (current_map_ * 2) + 1] << 8);
+  
+  // Overlay ID input
+  if (gui::InputHexWord("Overlay ID", &current_overlay, 100)) {
+    // Write to ROM
+    (*rom_)[zelda3::OverworldCustomSubscreenOverlayArray + (current_map_ * 2)] = current_overlay & 0xFF;
+    (*rom_)[zelda3::OverworldCustomSubscreenOverlayArray + (current_map_ * 2) + 1] = (current_overlay >> 8) & 0xFF;
+    
+    // Update the overworld map
+    overworld_.mutable_overworld_map(current_map_)->set_subscreen_overlay(current_overlay);
+    
+    // Refresh the map
+    RefreshOverworldMap();
+  }
+  
+  Separator();
+  
+  // Show overlay information
+  Text("Overlay Information:");
+  Text("ID: 0x%04X", current_overlay);
+  
+  if (current_overlay == 0x00FF) {
+    Text("No overlay");
+  } else if (current_overlay == 0x009D) {
+    Text("Fog 2 (Lost Woods/Skull Woods)");
+  } else if (current_overlay == 0x0095) {
+    Text("Sky Background (Death Mountain)");
+  } else if (current_overlay == 0x009C) {
+    Text("Lava (Dark World Death Mountain)");
+  } else if (current_overlay == 0x0096) {
+    Text("Pyramid Background");
+  } else if (current_overlay == 0x0097) {
+    Text("Fog 1 (Master Sword Area)");
+  } else if (current_overlay == 0x0093) {
+    Text("Triforce Room Curtains");
+  } else {
+    Text("Custom overlay");
+  }
+}
+
+void OverworldEditor::DrawMapLockControls() {
+  if (current_map_lock_) {
+    PushStyleColor(ImGuiCol_Text, ImVec4(1.0f, 0.5f, 0.0f, 1.0f));
+    Text("Map Locked: %d (0x%02X)", current_map_, current_map_);
+    PopStyleColor();
+    
+    if (Button("Unlock Map")) {
+      current_map_lock_ = false;
+    }
+  } else {
+    Text("Map: %d (0x%02X) - Click to lock", current_map_, current_map_);
+    if (Button("Lock Map")) {
+      current_map_lock_ = true;
+    }
+  }
+}
+
+void OverworldEditor::DrawOverworldContextMenu() {
+  // Get the current map from mouse position
+  auto mouse_position = ow_map_canvas_.drawn_tile_position();
+  int map_x = mouse_position.x / kOverworldMapSize;
+  int map_y = mouse_position.y / kOverworldMapSize;
+  int hovered_map = map_x + map_y * 8;
+  if (current_world_ == 1) {
+    hovered_map += 0x40;
+  } else if (current_world_ == 2) {
+    hovered_map += 0x80;
+  }
+  
+  // Only show context menu if we're hovering over a valid map
+  if (hovered_map >= 0 && hovered_map < 0xA0) {
+    if (ImGui::BeginPopupContextWindow("OverworldMapContext")) {
+      Text("Map %d (0x%02X)", hovered_map, hovered_map);
+      Separator();
+      
+      // Map lock controls
+      if (current_map_lock_ && current_map_ == hovered_map) {
+        PushStyleColor(ImGuiCol_Text, ImVec4(1.0f, 0.5f, 0.0f, 1.0f));
+        Text("Currently Locked");
+        PopStyleColor();
+        if (MenuItem("Unlock Map")) {
+          current_map_lock_ = false;
+        }
+      } else {
+        if (MenuItem("Lock to This Map")) {
+          current_map_lock_ = true;
+          current_map_ = hovered_map;
+        }
+      }
+      
+      Separator();
+      
+      // Quick access to map settings
+      if (MenuItem("Map Properties")) {
+        show_properties_editor_ = true;
+        current_map_ = hovered_map;
+      }
+      
+      // Custom overworld features (only show if v3+)
+      static uint8_t asm_version = (*rom_)[zelda3::OverworldCustomASMHasBeenApplied];
+      if (asm_version >= 3 && asm_version != 0xFF) {
+        if (MenuItem("Custom Background Color")) {
+          show_custom_bg_color_editor_ = true;
+          current_map_ = hovered_map;
+        }
+        
+        if (MenuItem("Overlay Settings")) {
+          show_overlay_editor_ = true;
+          current_map_ = hovered_map;
+        }
+      }
+      
+      Separator();
+      
+      // Canvas controls
+      if (MenuItem("Reset Canvas Position")) {
+        ow_map_canvas_.set_scrolling(ImVec2(0, 0));
+      }
+      
+      if (MenuItem("Zoom to Fit")) {
+        ow_map_canvas_.set_global_scale(1.0f);
+        ow_map_canvas_.set_scrolling(ImVec2(0, 0));
+      }
+      
+      ImGui::EndPopup();
+    }
+  }
+}
+
 void OverworldEditor::DrawOverworldProperties() {
   static bool init_properties = false;
 
diff --git a/src/app/editor/overworld/overworld_editor.h b/src/app/editor/overworld/overworld_editor.h
index 12b931f0..e4dc3362 100644
--- a/src/app/editor/overworld/overworld_editor.h
+++ b/src/app/editor/overworld/overworld_editor.h
@@ -158,6 +158,10 @@ class OverworldEditor : public Editor, public gfx::GfxContext {
   absl::Status LoadSpriteGraphics();
 
   void DrawOverworldProperties();
+  void DrawCustomBackgroundColorEditor();
+  void DrawOverlayEditor();
+  void DrawMapLockControls();
+  void DrawOverworldContextMenu();
 
   absl::Status UpdateUsageStats();
   void DrawUsageGrid();
@@ -215,6 +219,9 @@ class OverworldEditor : public Editor, public gfx::GfxContext {
   bool middle_mouse_dragging_ = false;
   bool is_dragging_entity_ = false;
   bool current_map_lock_ = false;
+  bool show_custom_bg_color_editor_ = false;
+  bool show_overlay_editor_ = false;
+  bool use_area_specific_bg_color_ = false;
 
   gfx::Tilemap tile16_blockset_;
 
@@ -258,7 +265,7 @@ class OverworldEditor : public Editor, public gfx::GfxContext {
                                    gui::CanvasGridSize::k16x16};
   gui::Canvas properties_canvas_;
 
-  gui::Table toolset_table_{"##ToolsetTable0", 22, kToolsetTableFlags};
+  gui::Table toolset_table_{"##ToolsetTable0", 25, kToolsetTableFlags};
   gui::Table map_settings_table_{kOWMapTable.data(), 8, kOWMapFlags,
                                  ImVec2(0, 0)};
 
diff --git a/src/app/gui/canvas.h b/src/app/gui/canvas.h
index 24d3ec70..c2ff0d49 100644
--- a/src/app/gui/canvas.h
+++ b/src/app/gui/canvas.h
@@ -165,6 +165,7 @@ class Canvas {
   auto draw_list() const { return draw_list_; }
   auto zero_point() const { return canvas_p0_; }
   auto scrolling() const { return scrolling_; }
+  void set_scrolling(ImVec2 scroll) { scrolling_ = scroll; }
   auto drawn_tile_position() const { return drawn_tile_pos_; }
   auto canvas_size() const { return canvas_sz_; }
   void set_global_scale(float scale) { global_scale_ = scale; }
diff --git a/src/app/zelda3/overworld/overworld_map.cc b/src/app/zelda3/overworld/overworld_map.cc
index f62833d2..34b47472 100644
--- a/src/app/zelda3/overworld/overworld_map.cc
+++ b/src/app/zelda3/overworld/overworld_map.cc
@@ -826,6 +826,16 @@ absl::Status OverworldMap::LoadPalette() {
 
 void OverworldMap::ProcessGraphicsBuffer(int index, int static_graphics_offset,
                                          int size, uint8_t *all_gfx) {
+  // Ensure we don't go out of bounds
+  int max_offset = static_graphics_offset * size + size;
+  if (max_offset > rom_->graphics_buffer().size()) {
+    // Fill with zeros if out of bounds
+    for (int i = 0; i < size; i++) {
+      current_gfx_[(index * size) + i] = 0x00;
+    }
+    return;
+  }
+  
   for (int i = 0; i < size; i++) {
     auto byte = all_gfx[i + (static_graphics_offset * size)];
     switch (index) {
@@ -842,10 +852,29 @@ void OverworldMap::ProcessGraphicsBuffer(int index, int static_graphics_offset,
 
 absl::Status OverworldMap::BuildTileset() {
   if (current_gfx_.size() == 0) current_gfx_.resize(0x10000, 0x00);
-  for (int i = 0; i < 0x10; i++) {
-    ProcessGraphicsBuffer(i, static_graphics_[i], 0x1000,
+  
+  // Process the 8 main graphics sheets (slots 0-7)
+  for (int i = 0; i < 8; i++) {
+    if (static_graphics_[i] != 0) {
+      ProcessGraphicsBuffer(i, static_graphics_[i], 0x1000,
+                            rom_->graphics_buffer().data());
+    }
+  }
+  
+  // Process sprite graphics (slots 8-15)
+  for (int i = 8; i < 16; i++) {
+    if (static_graphics_[i] != 0) {
+      ProcessGraphicsBuffer(i, static_graphics_[i], 0x1000,
+                            rom_->graphics_buffer().data());
+    }
+  }
+  
+  // Process animated graphics if available (slot 16)
+  if (static_graphics_[16] != 0) {
+    ProcessGraphicsBuffer(7, static_graphics_[16], 0x1000,
                           rom_->graphics_buffer().data());
   }
+  
   return absl::OkStatus();
 }
 
diff --git a/src/app/zelda3/overworld/overworld_map.h b/src/app/zelda3/overworld/overworld_map.h
index 2b2468aa..dd059773 100644
--- a/src/app/zelda3/overworld/overworld_map.h
+++ b/src/app/zelda3/overworld/overworld_map.h
@@ -26,34 +26,21 @@ constexpr int OverworldCustomAreaSpecificBGPalette = 0x140000;
 // 1 byte, not 0 if enabled
 constexpr int OverworldCustomAreaSpecificBGEnabled = 0x140140;
 
+// Additional v3 constants
+constexpr int OverworldCustomSubscreenOverlayArray = 0x140340;  // 2 bytes for each overworld area (0x140)
+constexpr int OverworldCustomSubscreenOverlayEnabled = 0x140144;  // 1 byte, not 0 if enabled
+constexpr int OverworldCustomAnimatedGFXArray = 0x1402A0;  // 1 byte for each overworld area (0xA0)
+constexpr int OverworldCustomAnimatedGFXEnabled = 0x140143;  // 1 byte, not 0 if enabled
+constexpr int OverworldCustomTileGFXGroupArray = 0x140480;  // 8 bytes for each overworld area (0x500)
+constexpr int OverworldCustomTileGFXGroupEnabled = 0x140148;  // 1 byte, not 0 if enabled
+constexpr int OverworldCustomMosaicArray = 0x140200;  // 1 byte for each overworld area (0xA0)
+constexpr int OverworldCustomMosaicEnabled = 0x140142;  // 1 byte, not 0 if enabled
+
 // 1 byte for each overworld area (0xA0)
 constexpr int OverworldCustomMainPaletteArray = 0x140160;
 // 1 byte, not 0 if enabled
 constexpr int OverworldCustomMainPaletteEnabled = 0x140141;
 
-// 1 byte for each overworld area (0xA0)
-constexpr int OverworldCustomMosaicArray = 0x140200;
-
-// 1 byte, not 0 if enabled
-constexpr int OverworldCustomMosaicEnabled = 0x140142;
-
-// 1 byte for each overworld area (0xA0)
-constexpr int OverworldCustomAnimatedGFXArray = 0x1402A0;
-
-// 1 byte, not 0 if enabled
-constexpr int OverworldCustomAnimatedGFXEnabled = 0x140143;
-
-// 2 bytes for each overworld area (0x140)
-constexpr int OverworldCustomSubscreenOverlayArray = 0x140340;
-
-// 1 byte, not 0 if enabled
-constexpr int OverworldCustomSubscreenOverlayEnabled = 0x140144;
-
-// 8 bytes for each overworld area (0x500)
-constexpr int OverworldCustomTileGFXGroupArray = 0x140480;
-
-// 1 byte, not 0 if enabled
-constexpr int OverworldCustomTileGFXGroupEnabled = 0x140148;
 
 // v3 expanded constants
 constexpr int kOverworldMessagesExpanded = 0x1417F8;
@@ -145,12 +132,24 @@ class OverworldMap : public gfx::GfxContext {
     area_specific_bg_color_ = color;
   }
 
+  auto subscreen_overlay() const { return subscreen_overlay_; }
+  void set_subscreen_overlay(uint16_t overlay) { subscreen_overlay_ = overlay; }
+
+  auto animated_gfx() const { return animated_gfx_; }
+  void set_animated_gfx(uint8_t gfx) { animated_gfx_ = gfx; }
+
+  auto custom_tileset(int index) const { return custom_gfx_ids_[index]; }
+  void set_custom_tileset(int index, uint8_t value) { custom_gfx_ids_[index] = value; }
+
   auto mutable_current_graphics() { return &current_gfx_; }
   auto mutable_area_graphics() { return &area_graphics_; }
   auto mutable_area_palette() { return &area_palette_; }
   auto mutable_sprite_graphics(int i) { return &sprite_graphics_[i]; }
   auto mutable_sprite_palette(int i) { return &sprite_palette_[i]; }
   auto mutable_message_id() { return &message_id_; }
+  auto mutable_main_palette() { return &main_palette_; }
+  auto mutable_animated_gfx() { return &animated_gfx_; }
+  auto mutable_subscreen_overlay() { return &subscreen_overlay_; }
   auto mutable_area_music(int i) { return &area_music_[i]; }
   auto mutable_static_graphics(int i) { return &static_graphics_[i]; }