Merge branch 'master' into viewport + added style tweak block when viewports are enabled

# Conflicts:
#	examples/example_glfw_opengl3/main.cpp
#	examples/example_sdl_opengl3/main.cpp
#	examples/example_win32_directx11/main.cpp

docs/CHANGELOG.txt

@@ -37,6 +37,8 @@ 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

@@ -28,13 +28,13 @@ int main(int, char**)
     ImGuiIO& io = ImGui::GetIO(); (void)io;
     //io.ConfigFlags |= ImGuiConfigFlags_NavEnableKeyboard;  // Enable Keyboard Controls
 
-    // Setup Platform/Renderer bindings
-    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

@@ -243,14 +243,14 @@
     ImGuiIO& io = ImGui::GetIO(); (void)io;
     //io.ConfigFlags |= ImGuiConfigFlags_NavEnableKeyboard;  // Enable Keyboard Controls
 
+    // 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

@@ -100,15 +100,15 @@ int main(int argc, char** argv)
     ImGuiIO& io = ImGui::GetIO(); (void)io;
     //io.ConfigFlags |= ImGuiConfigFlags_NavEnableKeyboard;  // Enable Keyboard Controls
 
+    // 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

@@ -46,14 +46,22 @@ 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. 

examples/example_glfw_opengl3/main.cpp

@@ -92,17 +92,21 @@ 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.

examples/example_glfw_vulkan/main.cpp

@@ -360,6 +360,18 @@ 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 = {};
@@ -374,10 +386,6 @@ 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

@@ -22,13 +22,13 @@ int main(int, char**)
     ImGuiIO& io = ImGui::GetIO(); (void)io;
     //io.ConfigFlags |= ImGuiConfigFlags_NavEnableKeyboard;  // Enable Keyboard Controls
 
-    // 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

@@ -44,14 +44,22 @@ 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. 

examples/example_sdl_opengl3/main.cpp

@@ -84,17 +84,21 @@ 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. 

examples/example_sdl_vulkan/main.cpp

@@ -341,6 +341,18 @@ 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 = {};
@@ -355,10 +367,6 @@ 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

@@ -121,14 +121,22 @@ 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

@@ -140,17 +140,21 @@ int main(int, char**)
     io.ConfigFlags |= ImGuiConfigFlags_DpiEnableScaleFonts;     // FIXME-DPI: THIS CURRENTLY DOESN'T WORK AS EXPECTED. DON'T USE IN USER APP!
     io.ConfigFlags |= ImGuiConfigFlags_DpiEnableScaleViewports; // FIXME-DPI
 
-    // 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

@@ -295,6 +295,18 @@ 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, 
@@ -302,10 +314,6 @@ 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

@@ -80,18 +80,15 @@ int main(int, char**)
     ImGui::CreateContext();
     ImGuiIO& io = ImGui::GetIO(); (void)io;
     io.ConfigFlags |= ImGuiConfigFlags_NavEnableKeyboard;       // Enable Keyboard Controls
-    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();
 
     // 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. 

imgui.cpp

@@ -4848,7 +4848,7 @@ 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