Merge branch 'viewport' into docking

# Conflicts:
#	examples/example_allegro5/main.cpp
#	examples/example_win32_directx9/main.cpp

docs/CHANGELOG.txt

@@ -55,6 +55,8 @@ Breaking Changes:
 
 - Renamed io.ConfigResizeWindowsFromEdges to io.ConfigWindowsResizeFromEdges and removed its [Beta] mark.
   The addition of new configuration options in the Docking branch is pushing for a little reorganization of those names.
+- Made it illegal to call Begin("") with an empty string. This somehow accidentally worked before but had various 
+  undesirable side-effect as the window would have ID zero. In particular it is causing problems in viewport/docking branches.
 
 Other Changes:
 - Added BETA api for Tab Bar/Tabs widgets: (#261, #351)

examples/example_allegro5/main.cpp

@@ -29,14 +29,13 @@ int main(int, char**)
     //io.ConfigFlags |= ImGuiConfigFlags_NavEnableKeyboard;  // Enable Keyboard Controls
     io.ConfigFlags |= ImGuiConfigFlags_DockingEnable;        // Enable Docking
 
-    // Setup Platform/Renderer bindings
->>>>>>> viewport
-    ImGui_ImplAllegro5_Init(display);
-
-    // Setup Style
+    // Setup Dear ImGui style
     ImGui::StyleColorsDark();
     //ImGui::StyleColorsClassic();
 
+    // Setup Platform/Renderer bindings
+    ImGui_ImplAllegro5_Init(display);
+
     // Load Fonts
     // - If no fonts are loaded, dear imgui will use the default font. You can also load multiple fonts and use ImGui::PushFont()/PopFont() to select them. 
     // - AddFontFromFileTTF() will return the ImFont* so you can store it if you need to select the font among multiple. 

examples/example_apple_metal/Shared/Renderer.mm

@@ -26,11 +26,9 @@
 
         IMGUI_CHECKVERSION();
         ImGui::CreateContext();
-        (void)ImGui::GetIO();
-        
-        ImGui_ImplMetal_Init(_device);
-
         ImGui::StyleColorsDark();
+
+        ImGui_ImplMetal_Init(_device);
     }
 
     return self;

examples/example_apple_opengl2/main.mm

@@ -244,14 +244,14 @@
     //io.ConfigFlags |= ImGuiConfigFlags_NavEnableKeyboard;     // Enable Keyboard Controls
     io.ConfigFlags |= ImGuiConfigFlags_DockingEnable;           // Enable Docking
 
+    // Setup Dear ImGui style
+    ImGui::StyleColorsDark();
+    //ImGui::StyleColorsClassic();
+
     // Setup Platform/Renderer bindings
     ImGui_ImplOSX_Init();
     ImGui_ImplOpenGL2_Init();
 
-    // Setup Style
-    ImGui::StyleColorsDark();
-    //ImGui::StyleColorsClassic();
-
     // Load Fonts
     // - If no fonts are loaded, dear imgui will use the default font. You can also load multiple fonts and use ImGui::PushFont()/PopFont() to select them.
     // - AddFontFromFileTTF() will return the ImFont* so you can store it if you need to select the font among multiple.

examples/example_freeglut_opengl2/main.cpp

@@ -101,15 +101,15 @@ int main(int argc, char** argv)
     //io.ConfigFlags |= ImGuiConfigFlags_NavEnableKeyboard;     // Enable Keyboard Controls
     io.ConfigFlags |= ImGuiConfigFlags_DockingEnable;           // Enable Docking
 
+    // Setup Dear ImGui style
+    ImGui::StyleColorsDark();
+    //ImGui::StyleColorsClassic();
+
     // Setup Platform/Renderer bindings
     ImGui_ImplFreeGLUT_Init();
     ImGui_ImplFreeGLUT_InstallFuncs();
     ImGui_ImplOpenGL2_Init();
 
-    // Setup Style
-    ImGui::StyleColorsDark();
-    //ImGui::StyleColorsClassic();
-
     // Load Fonts
     // - If no fonts are loaded, dear imgui will use the default font. You can also load multiple fonts and use ImGui::PushFont()/PopFont() to select them. 
     // - AddFontFromFileTTF() will return the ImFont* so you can store it if you need to select the font among multiple. 

examples/example_glfw_opengl2/main.cpp

@@ -47,14 +47,22 @@ int main(int, char**)
     //io.ConfigFlags |= ImGuiConfigFlags_ViewportsNoTaskBarIcons;
     //io.ConfigFlags |= ImGuiConfigFlags_ViewportsNoMerge;
 
+    // Setup Dear ImGui style
+    ImGui::StyleColorsDark();
+    //ImGui::StyleColorsClassic();
+
+    // When viewports are enabled we tweak WindowRounding/WindowBg so platform windows can look identical to regular ones.
+    ImGuiStyle& style = ImGui::GetStyle();
+    if (io.ConfigFlags & ImGuiConfigFlags_ViewportsEnable)
+    {
+        style.WindowRounding = 0.0f;
+        style.Colors[ImGuiCol_WindowBg].w = 1.0f;
+    }
+
     // Setup Platform/Renderer bindings
     ImGui_ImplGlfw_InitForOpenGL(window, true);
     ImGui_ImplOpenGL2_Init();
 
-    // Setup Style
-    ImGui::StyleColorsDark();
-    //ImGui::StyleColorsClassic();
-
     // Load Fonts
     // - If no fonts are loaded, dear imgui will use the default font. You can also load multiple fonts and use ImGui::PushFont()/PopFont() to select them. 
     // - AddFontFromFileTTF() will return the ImFont* so you can store it if you need to select the font among multiple. 
@@ -141,9 +149,9 @@ int main(int, char**)
         {
             ImGui::UpdatePlatformWindows();
             ImGui::RenderPlatformWindowsDefault();
+            glfwMakeContextCurrent(window);
         }
 
-        glfwMakeContextCurrent(window);
         glfwSwapBuffers(window);
     }
 

examples/example_glfw_opengl3/main.cpp

@@ -93,17 +93,21 @@ int main(int, char**)
     //io.ConfigFlags |= ImGuiConfigFlags_ViewportsNoTaskBarIcons;
     //io.ConfigFlags |= ImGuiConfigFlags_ViewportsNoMerge;
 
-    // Setup Platform/Renderer bindings
-    ImGui_ImplGlfw_InitForOpenGL(window, true);
-    ImGui_ImplOpenGL3_Init(glsl_version);
-
-    // Setup Style
+    // Setup Dear ImGui style
     ImGui::StyleColorsDark();
     //ImGui::StyleColorsClassic();
 
+    // When viewports are enabled we tweak WindowRounding/WindowBg so platform windows can look identical to regular ones.
     ImGuiStyle& style = ImGui::GetStyle();
-    style.WindowRounding = 0.0f;                                // When viewports are enabled it is preferable to disable WinodwRounding
-    style.Colors[ImGuiCol_WindowBg].w = 1.0f;                   // When viewports are enabled it is preferable to disable WindowBg alpha
+    if (io.ConfigFlags & ImGuiConfigFlags_ViewportsEnable)
+    {
+        style.WindowRounding = 0.0f;
+        style.Colors[ImGuiCol_WindowBg].w = 1.0f;
+    }
+
+    // Setup Platform/Renderer bindings
+    ImGui_ImplGlfw_InitForOpenGL(window, true);
+    ImGui_ImplOpenGL3_Init(glsl_version);
 
     // Load Fonts
     // - If no fonts are loaded, dear imgui will use the default font. You can also load multiple fonts and use ImGui::PushFont()/PopFont() to select them.
@@ -179,7 +183,6 @@ int main(int, char**)
         // Rendering
         ImGui::Render();
         int display_w, display_h;
-        glfwMakeContextCurrent(window);
         glfwGetFramebufferSize(window, &display_w, &display_h);
         glViewport(0, 0, display_w, display_h);
         glClearColor(clear_color.x, clear_color.y, clear_color.z, clear_color.w);
@@ -191,9 +194,9 @@ int main(int, char**)
         {
             ImGui::UpdatePlatformWindows();
             ImGui::RenderPlatformWindowsDefault();
+            glfwMakeContextCurrent(window);
         }
 
-        glfwMakeContextCurrent(window);
         glfwSwapBuffers(window);
     }
 

examples/example_glfw_vulkan/main.cpp

@@ -361,6 +361,18 @@ int main(int, char**)
     //io.ConfigFlags |= ImGuiConfigFlags_ViewportsNoTaskBarIcons;
     //io.ConfigFlags |= ImGuiConfigFlags_ViewportsNoMerge;
 
+    // Setup Dear ImGui style
+    ImGui::StyleColorsDark();
+    //ImGui::StyleColorsClassic();
+
+    // When viewports are enabled we tweak WindowRounding/WindowBg so platform windows can look identical to regular ones.
+    ImGuiStyle& style = ImGui::GetStyle();
+    if (io.ConfigFlags & ImGuiConfigFlags_ViewportsEnable)
+    {
+        style.WindowRounding = 0.0f;
+        style.Colors[ImGuiCol_WindowBg].w = 1.0f;
+    }
+
     // Setup Platform/Renderer bindings
     ImGui_ImplGlfw_InitForVulkan(window, true);
     ImGui_ImplVulkan_InitInfo init_info = {};
@@ -375,10 +387,6 @@ int main(int, char**)
     init_info.CheckVkResultFn = check_vk_result;
     ImGui_ImplVulkan_Init(&init_info, wd->RenderPass);
 
-    // Setup Style
-    ImGui::StyleColorsDark();
-    //ImGui::StyleColorsClassic();
-
     // Load Fonts
     // - If no fonts are loaded, dear imgui will use the default font. You can also load multiple fonts and use ImGui::PushFont()/PopFont() to select them. 
     // - AddFontFromFileTTF() will return the ImFont* so you can store it if you need to select the font among multiple. 

examples/example_marmalade/main.cpp

@@ -23,13 +23,13 @@ int main(int, char**)
     //io.ConfigFlags |= ImGuiConfigFlags_NavEnableKeyboard;  // Enable Keyboard Controls
     io.ConfigFlags |= ImGuiConfigFlags_DockingEnable;        // Enable Docking
 
-    // Setup Platform/Renderer bindings
-    ImGui_Marmalade_Init(true);
-
-    // Setup Style
+    // Setup Dear ImGui style
     ImGui::StyleColorsDark();
     //ImGui::StyleColorsClassic();
 
+    // Setup Platform/Renderer bindings
+    ImGui_Marmalade_Init(true);
+
     // Load Fonts
     // - If no fonts are loaded, dear imgui will use the default font. You can also load multiple fonts and use ImGui::PushFont()/PopFont() to select them. 
     // - AddFontFromFileTTF() will return the ImFont* so you can store it if you need to select the font among multiple. 

examples/example_sdl_opengl2/main.cpp

@@ -32,6 +32,7 @@ int main(int, char**)
     SDL_GetCurrentDisplayMode(0, &current);
     SDL_Window* window = SDL_CreateWindow("Dear ImGui SDL2+OpenGL example", SDL_WINDOWPOS_CENTERED, SDL_WINDOWPOS_CENTERED, 1280, 720, SDL_WINDOW_OPENGL|SDL_WINDOW_RESIZABLE);
     SDL_GLContext gl_context = SDL_GL_CreateContext(window);
+    SDL_GL_MakeCurrent(window, gl_context);
     SDL_GL_SetSwapInterval(1); // Enable vsync
 
     // Setup Dear ImGui context
@@ -44,14 +45,22 @@ int main(int, char**)
     //io.ConfigFlags |= ImGuiConfigFlags_ViewportsNoTaskBarIcons;
     //io.ConfigFlags |= ImGuiConfigFlags_ViewportsNoMerge;
 
+    // Setup Dear ImGui style
+    ImGui::StyleColorsDark();
+    //ImGui::StyleColorsClassic();
+
+    // When viewports are enabled we tweak WindowRounding/WindowBg so platform windows can look identical to regular ones.
+    ImGuiStyle& style = ImGui::GetStyle();
+    if (io.ConfigFlags & ImGuiConfigFlags_ViewportsEnable)
+    {
+        style.WindowRounding = 0.0f;
+        style.Colors[ImGuiCol_WindowBg].w = 1.0f;
+    }
+
     // Setup Platform/Renderer bindings
     ImGui_ImplSDL2_InitForOpenGL(window, gl_context);
     ImGui_ImplOpenGL2_Init();
 
-    // Setup Style
-    ImGui::StyleColorsDark();
-    //ImGui::StyleColorsClassic();
-
     // Load Fonts
     // - If no fonts are loaded, dear imgui will use the default font. You can also load multiple fonts and use ImGui::PushFont()/PopFont() to select them. 
     // - AddFontFromFileTTF() will return the ImFont* so you can store it if you need to select the font among multiple. 
@@ -143,9 +152,9 @@ int main(int, char**)
         {
             ImGui::UpdatePlatformWindows();
             ImGui::RenderPlatformWindowsDefault();
+            SDL_GL_MakeCurrent(window, gl_context);
         }
 
-        SDL_GL_MakeCurrent(window, gl_context);
         SDL_GL_SwapWindow(window);
     }
 

examples/example_sdl_opengl3/main.cpp

@@ -56,6 +56,7 @@ int main(int, char**)
     SDL_GetCurrentDisplayMode(0, &current);
     SDL_Window* window = SDL_CreateWindow("Dear ImGui SDL2+OpenGL3 example", SDL_WINDOWPOS_CENTERED, SDL_WINDOWPOS_CENTERED, 1280, 720, SDL_WINDOW_OPENGL|SDL_WINDOW_RESIZABLE);
     SDL_GLContext gl_context = SDL_GL_CreateContext(window);
+    SDL_GL_MakeCurrent(window, gl_context);
     SDL_GL_SetSwapInterval(1); // Enable vsync
 
     // Initialize OpenGL loader
@@ -84,17 +85,21 @@ int main(int, char**)
     //io.ConfigFlags |= ImGuiConfigFlags_ViewportsNoTaskBarIcons;
     //io.ConfigFlags |= ImGuiConfigFlags_ViewportsNoMerge;
 
-    // Setup Platform/Renderer bindings
-    ImGui_ImplSDL2_InitForOpenGL(window, gl_context);
-    ImGui_ImplOpenGL3_Init(glsl_version);
-
-    // Setup Style
+    // Setup Dear ImGui style
     ImGui::StyleColorsDark();
     //ImGui::StyleColorsClassic();
 
+    // When viewports are enabled we tweak WindowRounding/WindowBg so platform windows can look identical to regular ones.
     ImGuiStyle& style = ImGui::GetStyle();
-    style.WindowRounding = 0.0f;                                // When viewports are enabled it is preferable to disable WinodwRounding
-    style.Colors[ImGuiCol_WindowBg].w = 1.0f;                   // When viewports are enabled it is preferable to disable WindowBg alpha
+    if (io.ConfigFlags & ImGuiConfigFlags_ViewportsEnable)
+    {
+        style.WindowRounding = 0.0f;
+        style.Colors[ImGuiCol_WindowBg].w = 1.0f;
+    }
+
+    // Setup Platform/Renderer bindings
+    ImGui_ImplSDL2_InitForOpenGL(window, gl_context);
+    ImGui_ImplOpenGL3_Init(glsl_version);
 
     // Load Fonts
     // - If no fonts are loaded, dear imgui will use the default font. You can also load multiple fonts and use ImGui::PushFont()/PopFont() to select them. 
@@ -178,7 +183,6 @@ int main(int, char**)
 
         // Rendering
         ImGui::Render();
-        SDL_GL_MakeCurrent(window, gl_context);
         glViewport(0, 0, (int)io.DisplaySize.x, (int)io.DisplaySize.y);
         glClearColor(clear_color.x, clear_color.y, clear_color.z, clear_color.w);
         glClear(GL_COLOR_BUFFER_BIT);
@@ -189,9 +193,9 @@ int main(int, char**)
         {
             ImGui::UpdatePlatformWindows();
             ImGui::RenderPlatformWindowsDefault();
+            SDL_GL_MakeCurrent(window, gl_context);
         }
 
-        SDL_GL_MakeCurrent(window, gl_context);
         SDL_GL_SwapWindow(window);
     }
 

examples/example_sdl_vulkan/main.cpp

@@ -342,6 +342,18 @@ int main(int, char**)
     //io.ConfigFlags |= ImGuiConfigFlags_ViewportsNoTaskBarIcons;
     //io.ConfigFlags |= ImGuiConfigFlags_ViewportsNoMerge;
 
+    // Setup Dear ImGui style
+    ImGui::StyleColorsDark();
+    //ImGui::StyleColorsClassic();
+
+    // When viewports are enabled we tweak WindowRounding/WindowBg so platform windows can look identical to regular ones.
+    ImGuiStyle& style = ImGui::GetStyle();
+    if (io.ConfigFlags & ImGuiConfigFlags_ViewportsEnable)
+    {
+        style.WindowRounding = 0.0f;
+        style.Colors[ImGuiCol_WindowBg].w = 1.0f;
+    }
+
     // Setup Platform/Renderer bindings
     ImGui_ImplSDL2_InitForVulkan(window);
     ImGui_ImplVulkan_InitInfo init_info = {};
@@ -356,10 +368,6 @@ int main(int, char**)
     init_info.CheckVkResultFn = check_vk_result;
     ImGui_ImplVulkan_Init(&init_info, wd->RenderPass);
 
-    // Setup Style
-    ImGui::StyleColorsDark();
-    //ImGui::StyleColorsClassic();
-
     // Load Fonts
     // - If no fonts are loaded, dear imgui will use the default font. You can also load multiple fonts and use ImGui::PushFont()/PopFont() to select them. 
     // - AddFontFromFileTTF() will return the ImFont* so you can store it if you need to select the font among multiple. 

examples/example_win32_directx10/main.cpp

@@ -122,14 +122,22 @@ int main(int, char**)
     //io.ConfigFlags |= ImGuiConfigFlags_ViewportsNoTaskBarIcons;
     //io.ConfigFlags |= ImGuiConfigFlags_ViewportsNoMerge;
 
+    // Setup Dear ImGui style
+    ImGui::StyleColorsDark();
+    //ImGui::StyleColorsClassic();
+
+    // When viewports are enabled we tweak WindowRounding/WindowBg so platform windows can look identical to regular ones.
+    ImGuiStyle& style = ImGui::GetStyle();
+    if (io.ConfigFlags & ImGuiConfigFlags_ViewportsEnable)
+    {
+        style.WindowRounding = 0.0f;
+        style.Colors[ImGuiCol_WindowBg].w = 1.0f;
+    }
+
     // Setup Platform/Renderer bindings
     ImGui_ImplWin32_Init(hwnd);
     ImGui_ImplDX10_Init(g_pd3dDevice);
 
-    // Setup Style
-    ImGui::StyleColorsDark();
-    //ImGui::StyleColorsClassic();
-
     // Load Fonts
     // - If no fonts are loaded, dear imgui will use the default font. You can also load multiple fonts and use ImGui::PushFont()/PopFont() to select them. 
     // - AddFontFromFileTTF() will return the ImFont* so you can store it if you need to select the font among multiple. 

examples/example_win32_directx11/main.cpp

@@ -141,17 +141,21 @@ int main(int, char**)
     io.ConfigFlags |= ImGuiConfigFlags_DpiEnableScaleViewports; // FIXME-DPI
     io.ConfigDockingWithShift = true;
 
-    // Setup Platform/Renderer bindings
-    ImGui_ImplWin32_Init(hwnd);
-    ImGui_ImplDX11_Init(g_pd3dDevice, g_pd3dDeviceContext);
-
-    // Setup Style
+    // Setup Dear ImGui style
     ImGui::StyleColorsDark();
     //ImGui::StyleColorsClassic();
 
+    // When viewports are enabled we tweak WindowRounding/WindowBg so platform windows can look identical to regular ones.
     ImGuiStyle& style = ImGui::GetStyle();
-    style.WindowRounding = 0.0f;                                // When viewports are enabled it is preferable to disable WinodwRounding
-    style.Colors[ImGuiCol_WindowBg].w = 1.0f;                   // When viewports are enabled it is preferable to disable WindowBg alpha
+    if (io.ConfigFlags & ImGuiConfigFlags_ViewportsEnable)
+    {
+        style.WindowRounding = 0.0f;
+        style.Colors[ImGuiCol_WindowBg].w = 1.0f;
+    }
+
+    // Setup Platform/Renderer bindings
+    ImGui_ImplWin32_Init(hwnd);
+    ImGui_ImplDX11_Init(g_pd3dDevice, g_pd3dDeviceContext);
 
     // Load Fonts
     // - If no fonts are loaded, dear imgui will use the default font. You can also load multiple fonts and use ImGui::PushFont()/PopFont() to select them. 

examples/example_win32_directx12/main.cpp

@@ -296,6 +296,18 @@ int main(int, char**)
     //io.ConfigFlags |= ImGuiConfigFlags_ViewportsNoTaskBarIcons;
     //io.ConfigFlags |= ImGuiConfigFlags_ViewportsNoMerge;
 
+    // Setup Dear ImGui style
+    ImGui::StyleColorsDark();
+    //ImGui::StyleColorsClassic();
+
+    // When viewports are enabled we tweak WindowRounding/WindowBg so platform windows can look identical to regular ones.
+    ImGuiStyle& style = ImGui::GetStyle();
+    if (io.ConfigFlags & ImGuiConfigFlags_ViewportsEnable)
+    {
+        style.WindowRounding = 0.0f;
+        style.Colors[ImGuiCol_WindowBg].w = 1.0f;
+    }
+
     // Setup Platform/Renderer bindings
     ImGui_ImplWin32_Init(hwnd);
     ImGui_ImplDX12_Init(g_pd3dDevice, NUM_FRAMES_IN_FLIGHT, 
@@ -303,10 +315,6 @@ int main(int, char**)
         g_pd3dSrvDescHeap->GetCPUDescriptorHandleForHeapStart(), 
         g_pd3dSrvDescHeap->GetGPUDescriptorHandleForHeapStart());
 
-    // Setup Style
-    ImGui::StyleColorsDark();
-    //ImGui::StyleColorsClassic();
-
     // Load Fonts
     // - If no fonts are loaded, dear imgui will use the default font. You can also load multiple fonts and use ImGui::PushFont()/PopFont() to select them. 
     // - AddFontFromFileTTF() will return the ImFont* so you can store it if you need to select the font among multiple. 

examples/example_win32_directx9/main.cpp

@@ -80,19 +80,22 @@ int main(int, char**)
     ImGui::CreateContext();
     ImGuiIO& io = ImGui::GetIO(); (void)io;
     io.ConfigFlags |= ImGuiConfigFlags_NavEnableKeyboard;       // Enable Keyboard Controls
+<<<<<<< HEAD
     io.ConfigFlags |= ImGuiConfigFlags_DockingEnable;           // Enable Docking
     io.ConfigFlags |= ImGuiConfigFlags_ViewportsEnable;         // Enable Multi-Viewport / Platform Windows
     //io.ConfigFlags |= ImGuiConfigFlags_ViewportsNoTaskBarIcons;
     //io.ConfigFlags |= ImGuiConfigFlags_ViewportsNoMerge;
+=======
+
+    // Setup Dear ImGui style
+    ImGui::StyleColorsDark();
+    //ImGui::StyleColorsClassic();
+>>>>>>> viewport
 
     // Setup Platform/Renderer bindings
     ImGui_ImplWin32_Init(hwnd);
     ImGui_ImplDX9_Init(g_pd3dDevice);
 
-    // Setup Style
-    ImGui::StyleColorsDark();
-    //ImGui::StyleColorsClassic();
-
     // Load Fonts
     // - If no fonts are loaded, dear imgui will use the default font. You can also load multiple fonts and use ImGui::PushFont()/PopFont() to select them. 
     // - AddFontFromFileTTF() will return the ImFont* so you can store it if you need to select the font among multiple. 

examples/imgui_impl_sdl.cpp

@@ -253,39 +253,39 @@ static void ImGui_ImplSDL2_UpdateMousePosAndButtons()
     io.MousePos = ImVec2(-FLT_MAX, -FLT_MAX);
 #endif
 
-    int mx, my;
-    Uint32 mouse_buttons = SDL_GetMouseState(&mx, &my);
+    int mouse_x, mouse_y;
+    Uint32 mouse_buttons = SDL_GetMouseState(&mouse_x, &mouse_y); // NB: We don't use the x/y results from SDL_GetMouseState()
+    SDL_GetGlobalMouseState(&mouse_x, &mouse_y);
     io.MouseDown[0] = g_MousePressed[0] || (mouse_buttons & SDL_BUTTON(SDL_BUTTON_LEFT)) != 0;  // If a mouse press event came, always pass it as "mouse held this frame", so we don't miss click-release events that are shorter than 1 frame.
     io.MouseDown[1] = g_MousePressed[1] || (mouse_buttons & SDL_BUTTON(SDL_BUTTON_RIGHT)) != 0;
     io.MouseDown[2] = g_MousePressed[2] || (mouse_buttons & SDL_BUTTON(SDL_BUTTON_MIDDLE)) != 0;
     g_MousePressed[0] = g_MousePressed[1] = g_MousePressed[2] = false;
 
 #if SDL_HAS_CAPTURE_MOUSE && !defined(__EMSCRIPTEN__)
-    SDL_Window* focused_window = SDL_GetKeyboardFocus();
-    if (focused_window)
+    if (io.ConfigFlags & ImGuiConfigFlags_ViewportsEnable)
     {
-        if (io.ConfigFlags & ImGuiConfigFlags_ViewportsEnable)
-        {
-            // Multi-viewport mode: mouse position in OS absolute coordinates (io.MousePos is (0,0) when the mouse is on the upper-left of the primary monitor)
-            SDL_GetGlobalMouseState(&mx, &my);
+        // Multi-viewport mode: mouse position in OS absolute coordinates (io.MousePos is (0,0) when the mouse is on the upper-left of the primary monitor)
+        if (SDL_Window* focused_window = SDL_GetKeyboardFocus())
             if (ImGui::FindViewportByPlatformHandle((void*)focused_window) != NULL)
-                io.MousePos = ImVec2((float)mx, (float)my);
-        }
-        else
+                io.MousePos = ImVec2((float)mouse_x, (float)mouse_y);
+    }
+    else
+#endif
+    {
+        // Single viewport mode: mouse position in client window coordinates (io.MousePos is (0,0) when the mouse is on the upper-left corner of the app window)
+        if (SDL_GetWindowFlags(g_Window) & SDL_WINDOW_INPUT_FOCUS)
         {
-            // Single viewport mode: mouse position in client window coordinates (io.MousePos is (0,0) when the mouse is on the upper-left corner of the app window)
-            if (focused_window == g_Window)
-                io.MousePos = ImVec2((float)mx, (float)my);
+            int window_x, window_y;
+            SDL_GetWindowPosition(g_Window, &window_x, &window_y);
+            io.MousePos = ImVec2((float)(mouse_x - window_x), (float)(mouse_y - window_y));
         }
     }
 
     // We already retrieve global mouse position, SDL_CaptureMouse() also let the OS know e.g. that our imgui drag outside the SDL window boundaries shouldn't trigger the OS window resize cursor
     // The function is only supported from SDL 2.0.4 (released Jan 2016)
+#if SDL_HAS_CAPTURE_MOUSE 
     bool any_mouse_button_down = ImGui::IsAnyMouseDown();
     SDL_CaptureMouse(any_mouse_button_down ? SDL_TRUE : SDL_FALSE);
-#else
-    if (SDL_GetWindowFlags(g_Window) & SDL_WINDOW_INPUT_FOCUS)
-        io.MousePos = ImVec2((float)mx, (float)my);
 #endif
 }
 

imgui.cpp

@@ -3895,6 +3895,7 @@ void ImGui::EndFrame()
             IM_ASSERT(viewport->Window != NULL);
         g.PlatformIO.Viewports.push_back(viewport);
     }
+    g.Viewports[0]->ClearRequestFlags(); // Clear main viewport flags because UpdatePlatformWindows() won't do it and may not even be called
 
     // Sort the window list so that all child windows are after their parent
     // We cannot do that on FocusWindow() because childs may not exist yet
@@ -4959,7 +4960,7 @@ bool ImGui::Begin(const char* name, bool* p_open, ImGuiWindowFlags flags)
 {
     ImGuiContext& g = *GImGui;
     const ImGuiStyle& style = g.Style;
-    IM_ASSERT(name != NULL);                        // Window name required
+    IM_ASSERT(name != NULL && name[0] != '\0');     // Window name required
     IM_ASSERT(g.FrameScopeActive);                  // Forgot to call ImGui::NewFrame()
     IM_ASSERT(g.FrameCountEnded != g.FrameCount);   // Called ImGui::Render() or ImGui::EndFrame() and haven't called ImGui::NewFrame() again yet
 
@@ -8005,7 +8006,7 @@ void ImGui::UpdatePlatformWindows()
         }
 
         // Clear request flags
-        viewport->PlatformRequestClose = viewport->PlatformRequestMove = viewport->PlatformRequestResize = false;
+        viewport->ClearRequestFlags();
     }
 
     // Update our implicit z-order knowledge of platform windows, which is used when the back-end cannot provide io.MouseHoveredViewport.
@@ -8110,7 +8111,7 @@ void ImGui::DestroyPlatformWindow(ImGuiViewportP* viewport)
     viewport->PlatformHandle = NULL;
     viewport->RendererUserData = viewport->PlatformHandle = NULL;
     viewport->PlatformWindowCreated = false;
-    viewport->PlatformRequestClose = viewport->PlatformRequestMove = viewport->PlatformRequestResize = false;
+    viewport->ClearRequestFlags();
 }
 
 void ImGui::DestroyPlatformWindows()

imgui_internal.h

@@ -690,10 +690,11 @@ struct ImGuiViewportP : public ImGuiViewport
     ImVec2              LastPlatformSize;
     ImVec2              LastRendererSize;
 
-    ImGuiViewportP()         { Idx = -1; LastFrameActive = LastFrameOverlayDrawList = LastFrontMostStampCount = -1; LastNameHash = 0; Alpha = LastAlpha = 1.0f; PlatformMonitor = -1; PlatformWindowCreated = PlatformWindowMinimized = false; Window = NULL; OverlayDrawList = NULL; LastPlatformPos = LastPlatformSize = LastRendererSize = ImVec2(FLT_MAX, FLT_MAX); }
-    ~ImGuiViewportP()        { if (OverlayDrawList) IM_DELETE(OverlayDrawList); }
-    ImRect  GetRect() const  { return ImRect(Pos.x, Pos.y, Pos.x + Size.x, Pos.y + Size.y); }
-    ImVec2  GetCenter() const{ return ImVec2(Pos.x + Size.x * 0.5f, Pos.y + Size.y * 0.5f); }
+    ImGuiViewportP()            { Idx = -1; LastFrameActive = LastFrameOverlayDrawList = LastFrontMostStampCount = -1; LastNameHash = 0; Alpha = LastAlpha = 1.0f; PlatformMonitor = -1; PlatformWindowCreated = PlatformWindowMinimized = false; Window = NULL; OverlayDrawList = NULL; LastPlatformPos = LastPlatformSize = LastRendererSize = ImVec2(FLT_MAX, FLT_MAX); }
+    ~ImGuiViewportP()           { if (OverlayDrawList) IM_DELETE(OverlayDrawList); }
+    ImRect  GetRect() const     { return ImRect(Pos.x, Pos.y, Pos.x + Size.x, Pos.y + Size.y); }
+    ImVec2  GetCenter() const   { return ImVec2(Pos.x + Size.x * 0.5f, Pos.y + Size.y * 0.5f); }
+    void    ClearRequestFlags() { PlatformRequestClose = PlatformRequestMove = PlatformRequestResize = false; }
 };
 
 struct ImGuiNavMoveResult