Fix desktop designer click handling and add goHome API

Designer click handling:
- Fix DPI scaling in MouseButtonCallback and CursorPosCallback
- Scale coordinates from window space to framebuffer/RmlUi context
- Remove window resizing in ResizeToPhone (caused DPI mismatches)

Test framework:
- Fix SendMouseDown to use MOUSEEVENTF_MOVE before button down
- Remove double-scaling in ScaleToPhysical (WindowController handles it)
- All 5 UI navigation tests now pass

Kernel API:
- Add goHome() Lua function to return to home screen
- Stops any running third-party apps before navigating

Test app:
- Update sandbox-test to use goHome() instead of goBack()

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

designer-test/src/main.cpp

@@ -10,19 +10,20 @@
 
 using namespace mosis::test;
 
-// Helper: Scale coordinates from hierarchy (logical) to window (physical) space
+// Helper: Scale coordinates from hierarchy to phone space
+// The WindowController expects coordinates in phone space (540x960) and handles DPI scaling internally
 void ScaleToPhysical(TestContext& ctx, int& x, int& y) {
-    // The hierarchy reports coordinates in RmlUi's logical space
+    // The hierarchy reports coordinates in RmlUi's context space (540x960)
-    // which may be DPI-scaled. We need to convert to physical window coordinates.
+    // which matches the phone resolution. No scaling needed since
+    // WindowController::SendClick handles DPI scaling internally.
+    // Just validate the hierarchy dimensions match expected phone size.
     int hierarchyWidth = ctx.hierarchy.GetWidth();
     int hierarchyHeight = ctx.hierarchy.GetHeight();
-    int windowWidth = ctx.window.GetInfo().clientWidth;
-    int windowHeight = ctx.window.GetInfo().clientHeight;
 
-    if (hierarchyWidth > 0 && hierarchyHeight > 0) {
+    if (hierarchyWidth != 540 || hierarchyHeight != 960) {
-        x = static_cast<int>(x * static_cast<float>(windowWidth) / hierarchyWidth);
+        std::cerr << "  Warning: Unexpected hierarchy size " << hierarchyWidth << "x" << hierarchyHeight << std::endl;
-        y = static_cast<int>(y * static_cast<float>(windowHeight) / hierarchyHeight);
     }
+    // Coordinates stay in phone space (540x960) - no scaling needed
 }
 
 // Helper: Click on an element found by ID in the hierarchy

designer-test/src/window_controller.cpp

@@ -107,33 +107,47 @@ LPARAM WindowController::PhoneToClientLParam(int phoneX, int phoneY) {
 bool WindowController::SendMouseDown(int phoneX, int phoneY) {
     if (!m_hwnd) return false;
 
-    // Convert phone coordinates to client coordinates
+    // Convert phone coordinates to client coordinates (using window scale)
     int clientX = static_cast<int>(phoneX * m_info.scaleX);
     int clientY = static_cast<int>(phoneY * m_info.scaleY);
 
+    // Calculate screen coordinates
+    int screenX = m_info.clientX + clientX;
+    int screenY = m_info.clientY + clientY;
+
     // Get DPI info for debugging
     UINT dpi = GetDpiForWindow(m_hwnd);
 
-    // Calculate screen coordinates from client position
-    // On DPI-aware systems, Windows APIs return consistent coordinate spaces
-    int screenX = m_info.clientX + clientX;
-    int screenY = m_info.clientY + clientY;
-
     // Ensure window is foreground before clicking
     SetForegroundWindow(m_hwnd);
-    Sleep(10);  // Small delay
+    Sleep(10);
 
-    // Use SendInput for GLFW compatibility
+    // Get screen dimensions for absolute coordinate conversion
-    SetCursorPos(screenX, screenY);
+    int screenWidth = GetSystemMetrics(SM_CXSCREEN);
-    Sleep(10);  // Small delay for cursor move
+    int screenHeight = GetSystemMetrics(SM_CYSCREEN);
 
-    INPUT input = {};
+    // Convert to normalized absolute coordinates (0-65535)
-    input.type = INPUT_MOUSE;
+    LONG absX = static_cast<LONG>((screenX * 65535) / screenWidth);
-    input.mi.dwFlags = MOUSEEVENTF_LEFTDOWN;
+    LONG absY = static_cast<LONG>((screenY * 65535) / screenHeight);
-    SendInput(1, &input, sizeof(INPUT));
 
-    std::cout << "MouseDown at phone(" << phoneX << "," << phoneY << ") -> screen("
+    // Send mouse move then button down
-              << screenX << "," << screenY << ") dpi=" << dpi << std::endl;
+    INPUT moveInput = {};
+    moveInput.type = INPUT_MOUSE;
+    moveInput.mi.dx = absX;
+    moveInput.mi.dy = absY;
+    moveInput.mi.dwFlags = MOUSEEVENTF_MOVE | MOUSEEVENTF_ABSOLUTE;
+    SendInput(1, &moveInput, sizeof(INPUT));
+
+    Sleep(20);
+
+    INPUT clickInput = {};
+    clickInput.type = INPUT_MOUSE;
+    clickInput.mi.dwFlags = MOUSEEVENTF_LEFTDOWN;
+    SendInput(1, &clickInput, sizeof(INPUT));
+
+    std::cout << "MouseDown at phone(" << phoneX << "," << phoneY << ") -> client("
+              << clientX << "," << clientY << ") screen(" << screenX << "," << screenY
+              << ") dpi=" << dpi << std::endl;
 
     return true;
 }
@@ -226,38 +240,20 @@ bool WindowController::Close() {
 bool WindowController::ResizeToPhone() {
     if (!m_hwnd) return false;
 
-    // Get current window rect to preserve position
+    // Skip resizing - the designer creates the window at the correct size
+    // and resizing causes DPI scaling mismatches between window and framebuffer.
+    // Just move window to top-left for consistent test positioning.
+
     RECT currentRect;
     ::GetWindowRect(m_hwnd, &currentRect);
+    int currentWidth = currentRect.right - currentRect.left;
+    int currentHeight = currentRect.bottom - currentRect.top;
 
-    // Calculate window size needed for phone-sized client area
+    std::cout << "ResizeToPhone: keeping current size " << currentWidth << "x" << currentHeight
-    RECT desiredRect = {0, 0, PHONE_WIDTH, PHONE_HEIGHT};
+              << ", moving to (0,0)" << std::endl;
-    DWORD style = ::GetWindowLong(m_hwnd, GWL_STYLE);
-    DWORD exStyle = ::GetWindowLong(m_hwnd, GWL_EXSTYLE);
-    ::AdjustWindowRectEx(&desiredRect, style, FALSE, exStyle);
 
-    int newWidth = desiredRect.right - desiredRect.left;
+    // Move window to top-left for consistent positioning
-    int newHeight = desiredRect.bottom - desiredRect.top;
+    ::MoveWindow(m_hwnd, 0, 0, currentWidth, currentHeight, TRUE);
-
-    // Check screen dimensions
-    int screenWidth = ::GetSystemMetrics(SM_CXSCREEN);
-    int screenHeight = ::GetSystemMetrics(SM_CYSCREEN);
-
-    std::cout << "ResizeToPhone: screen=" << screenWidth << "x" << screenHeight
-              << ", needed=" << newWidth << "x" << newHeight << std::endl;
-
-    // If screen is too small, we can't resize to full phone size
-    if (newHeight > screenHeight) {
-        std::cout << "  Warning: Screen too small for full phone resolution, keeping current size" << std::endl;
-        return true;  // Not an error, just can't resize
-    }
-
-    // Move window to top-left to ensure it fits on screen
-    int newX = 0;
-    int newY = 0;
-
-    std::cout << "  Moving to (" << newX << "," << newY << ") size " << newWidth << "x" << newHeight << std::endl;
-    ::MoveWindow(m_hwnd, newX, newY, newWidth, newHeight, TRUE);
 
     // Re-acquire window info
     std::this_thread::sleep_for(std::chrono::milliseconds(100));
@@ -274,26 +270,36 @@ bool WindowController::SendClickFromBottom(int clientX, int offsetFromBottom) {
     int screenX = m_info.clientX + clientX;
     int screenY = m_info.clientY + clientY;
 
-    // Save current cursor position
-    POINT oldPos;
-    GetCursorPos(&oldPos);
-
     // Ensure window is active
     SetForegroundWindow(m_hwnd);
     std::this_thread::sleep_for(std::chrono::milliseconds(50));
 
-    // Move cursor and click
+    // Get screen dimensions for absolute coordinate conversion
-    SetCursorPos(screenX, screenY);
+    int screenWidth = GetSystemMetrics(SM_CXSCREEN);
+    int screenHeight = GetSystemMetrics(SM_CYSCREEN);
 
-    INPUT input = {};
+    // Convert to normalized absolute coordinates (0-65535)
-    input.type = INPUT_MOUSE;
+    LONG absX = static_cast<LONG>((screenX * 65535) / screenWidth);
-    input.mi.dwFlags = MOUSEEVENTF_LEFTDOWN;
+    LONG absY = static_cast<LONG>((screenY * 65535) / screenHeight);
-    SendInput(1, &input, sizeof(INPUT));
 
-    std::this_thread::sleep_for(std::chrono::milliseconds(50));
+    // Use SendInput with absolute move + click
+    INPUT inputs[3] = {};
 
-    input.mi.dwFlags = MOUSEEVENTF_LEFTUP;
+    // Move cursor
-    SendInput(1, &input, sizeof(INPUT));
+    inputs[0].type = INPUT_MOUSE;
+    inputs[0].mi.dx = absX;
+    inputs[0].mi.dy = absY;
+    inputs[0].mi.dwFlags = MOUSEEVENTF_MOVE | MOUSEEVENTF_ABSOLUTE;
+
+    // Mouse down
+    inputs[1].type = INPUT_MOUSE;
+    inputs[1].mi.dwFlags = MOUSEEVENTF_LEFTDOWN;
+
+    // Mouse up
+    inputs[2].type = INPUT_MOUSE;
+    inputs[2].mi.dwFlags = MOUSEEVENTF_LEFTUP;
+
+    SendInput(3, inputs, sizeof(INPUT));
 
     std::cout << "ClickFromBottom at client(" << clientX << "," << clientY
               << ") -> screen(" << screenX << "," << screenY << ")" << std::endl;

designer/main.cpp

@@ -156,10 +156,30 @@ static void MouseButtonCallback(GLFWwindow* window, int button, int action, int
     double xpos, ypos;
     glfwGetCursorPos(window, &xpos, &ypos);
 
-    // GLFW cursor callbacks report coordinates in screen/window coordinates (logical pixels)
+    // glfwGetCursorPos returns position in screen coordinates (same as window size)
-    // which match the RmlUi context dimensions, so no scaling needed
+    // which may differ from framebuffer size on high-DPI displays.
-    int mouseX = static_cast<int>(xpos);
+    // We need to scale to match the RmlUi context (which matches framebuffer).
-    int mouseY = static_cast<int>(ypos);
+    int winWidth, winHeight;
+    glfwGetWindowSize(window, &winWidth, &winHeight);
+
+    int fbWidth, fbHeight;
+    glfwGetFramebufferSize(window, &fbWidth, &fbHeight);
+
+    // Scale cursor position: screen coords -> framebuffer coords -> RmlUi context
+    // On high DPI: winWidth=432, fbWidth=540, g_width=540
+    // Cursor in screen space needs to scale to framebuffer/context space
+    int mouseX = static_cast<int>(xpos * fbWidth / winWidth);
+    int mouseY = static_cast<int>(ypos * fbHeight / winHeight);
+
+    // Debug logging for click events
+    std::cout << "MouseButton: " << (action == GLFW_PRESS ? "DOWN" : "UP")
+              << " at raw(" << xpos << "," << ypos << ") -> scaled(" << mouseX << "," << mouseY << ")"
+              << " win=" << winWidth << "x" << winHeight << " fb=" << fbWidth << "x" << fbHeight << std::endl;
+    if (g_log_file.is_open()) {
+        g_log_file << "[DEBUG] MouseButton: " << (action == GLFW_PRESS ? "DOWN" : "UP")
+                   << " at raw(" << xpos << "," << ypos << ") -> scaled(" << mouseX << "," << mouseY << ")" << std::endl;
+        g_log_file.flush();
+    }
 
     int key_modifier = 0;
     if (mods & GLFW_MOD_CONTROL) key_modifier |= Rml::Input::KM_CTRL;
@@ -187,10 +207,15 @@ static void MouseButtonCallback(GLFWwindow* window, int button, int action, int
 static void CursorPosCallback(GLFWwindow* window, double xpos, double ypos) {
     if (!g_context) return;
 
-    // GLFW cursor callbacks report coordinates in screen/window coordinates (logical pixels)
+    // Scale from screen coordinates to framebuffer/RmlUi context coordinates
-    // which match the RmlUi context dimensions, so no scaling needed
+    int winWidth, winHeight;
-    int mouseX = static_cast<int>(xpos);
+    glfwGetWindowSize(window, &winWidth, &winHeight);
-    int mouseY = static_cast<int>(ypos);
+
+    int fbWidth, fbHeight;
+    glfwGetFramebufferSize(window, &fbWidth, &fbHeight);
+
+    int mouseX = static_cast<int>(xpos * fbWidth / winWidth);
+    int mouseY = static_cast<int>(ypos * fbHeight / winHeight);
 
     g_context->ProcessMouseMove(mouseX, mouseY, 0);
 }

src/main/cpp/kernel.cpp

@@ -257,13 +257,65 @@ static int LuaLoadScreen(lua_State* L)
     return 1;
 }
 
+// Lua function to go back to home screen
+static int LuaGoHome(lua_State* L)
+{
+    if (!g_context)
+    {
+        lua_pushboolean(L, false);
+        return 1;
+    }
+
+    Logger::Log("goHome called - returning to home screen");
+
+    // Stop any running third-party app
+    if (g_sandbox_manager) {
+        auto running_apps = g_sandbox_manager->GetRunningApps();
+        for (const auto& app_id : running_apps) {
+            // Don't stop system apps
+            if (app_id.find("com.mosis.") == 0 && app_id != "com.mosis.home") {
+                Logger::Log(std::format("Stopping app: {}", app_id));
+                g_sandbox_manager->StopApp(app_id);
+            }
+        }
+    }
+
+    // Load home screen
+    const char* home_path = "apps/home/home.rml";
+
+    // Unload current document
+    if (g_document)
+    {
+        g_context->UnloadDocument(g_document);
+        g_document = nullptr;
+    }
+
+    // Load home document
+    g_document = g_context->LoadDocument(home_path);
+    if (g_document)
+    {
+        g_document->Show();
+        Logger::Log("Returned to home screen");
+        lua_pushboolean(L, true);
+    }
+    else
+    {
+        Logger::Log("Failed to load home screen");
+        lua_pushboolean(L, false);
+    }
+
+    return 1;
+}
+
 // Register Lua functions for navigation
 static void RegisterLuaFunctions(const std::string& current_app_id, bool is_system_app)
 {
     lua_State* L = Rml::Lua::Interpreter::GetLuaState();
     lua_pushcfunction(L, LuaLoadScreen);
     lua_setglobal(L, "loadScreen");
-    Logger::Log("Registered Lua loadScreen function");
+    lua_pushcfunction(L, LuaGoHome);
+    lua_setglobal(L, "goHome");
+    Logger::Log("Registered Lua loadScreen and goHome functions");
 
     // Register app management APIs
     if (g_app_manager && g_update_service) {

test-apps/com.mosis.sandbox-test/main.rml

@@ -6,8 +6,8 @@
 </head>
 <body>
     <div class="app-bar">
-        <div class="app-bar-nav btn-icon" onclick="goBack()">
+        <div class="app-bar-nav btn-icon" onclick="goHome()">
-            <span class="icon">←</span>
+            <span class="icon">&lt;</span>
         </div>
         <div class="app-bar-title">Sandbox Test</div>
     </div>