Viewports: added void* ImGuiPlatformMonitor::PlatformHandle field (backend-dependant).

backends/imgui_impl_glfw.cpp

@@ -906,6 +906,7 @@ static void ImGui_ImplGlfw_UpdateMonitors()
         glfwGetMonitorContentScale(glfw_monitors[n], &x_scale, &y_scale);
         monitor.DpiScale = x_scale;
 #endif
+        monitor.PlatformHandle = (void*)glfw_monitors[n]; // [...] GLFW doc states: "guaranteed to be valid only until the monitor configuration changes"
         platform_io.Monitors.push_back(monitor);
     }
 }

backends/imgui_impl_osx.mm

@@ -1048,6 +1048,7 @@ static void ImGui_ImplOSX_UpdateMonitors()
         imgui_monitor.WorkPos = ImVec2(visibleFrame.origin.x, visibleFrame.origin.y);
         imgui_monitor.WorkSize = ImVec2(visibleFrame.size.width, visibleFrame.size.height);
         imgui_monitor.DpiScale = screen.backingScaleFactor;
+        imgui_monitor.PlatformHandle = (__bridge_retained void*)screen;
 
         platform_io.Monitors.push_back(imgui_monitor);
     }

backends/imgui_impl_sdl2.cpp

@@ -718,6 +718,7 @@ static void ImGui_ImplSDL2_UpdateMonitors()
         if (!SDL_GetDisplayDPI(n, &dpi, nullptr, nullptr))
             monitor.DpiScale = dpi / 96.0f;
 #endif
+        monitor.PlatformHandle = (void*)(intptr_t)n;
         platform_io.Monitors.push_back(monitor);
     }
 }

backends/imgui_impl_sdl3.cpp

@@ -643,6 +643,7 @@ static void ImGui_ImplSDL3_UpdateMonitors()
         //  DpiScale to cocoa_window.backingScaleFactor here.
         const SDL_DisplayMode* display_mode = SDL_GetCurrentDisplayMode(display_id);
         monitor.DpiScale = display_mode->display_scale;
+        monitor.PlatformHandle = (void*)(intptr_t)n;
         platform_io.Monitors.push_back(monitor);
     }
 }

backends/imgui_impl_win32.cpp

@@ -404,6 +404,7 @@ static BOOL CALLBACK ImGui_ImplWin32_UpdateMonitors_EnumFunc(HMONITOR monitor, H
     imgui_monitor.WorkPos = ImVec2((float)info.rcWork.left, (float)info.rcWork.top);
     imgui_monitor.WorkSize = ImVec2((float)(info.rcWork.right - info.rcWork.left), (float)(info.rcWork.bottom - info.rcWork.top));
     imgui_monitor.DpiScale = ImGui_ImplWin32_GetDpiScaleForMonitor(monitor);
+    imgui_monitor.PlatformHandle = (void*)monitor;
     ImGuiPlatformIO& io = ImGui::GetPlatformIO();
     if (info.dwFlags & MONITORINFOF_PRIMARY)
         io.Monitors.push_front(imgui_monitor);

docs/CHANGELOG.txt

@@ -122,6 +122,11 @@ Other changes:
 - Examples: Added native Win32+OpenGL3 example. We don't recommend using this setup but we
   provide it for completeness. (#3218, #5170, #6086, #2772, #2600, #2359, #2022, #1553) [@learn-more]
 
+Docking+Viewports Branch:
+
+- Viewports: added void* ImGuiPlatformMonitor::PlatformHandle field (backend-dependant),
+  for usage by user code.
+
 
 -----------------------------------------------------------------------
  VERSION 1.89.5 (Released 2023-04-13)

imgui.h

@@ -3250,7 +3250,8 @@ struct ImGuiPlatformMonitor
     ImVec2  MainPos, MainSize;      // Coordinates of the area displayed on this monitor (Min = upper left, Max = bottom right)
     ImVec2  WorkPos, WorkSize;      // Coordinates without task bars / side bars / menu bars. Used to avoid positioning popups/tooltips inside this region. If you don't have this info, please copy the value for MainPos/MainSize.
     float   DpiScale;               // 1.0f = 96 DPI
-    ImGuiPlatformMonitor()          { MainPos = MainSize = WorkPos = WorkSize = ImVec2(0, 0); DpiScale = 1.0f; }
+    void*   PlatformHandle;         // Backend dependant data (e.g. HMONITOR, GLFWmonitor*, SDL Display Index, NSScreen*)
+    ImGuiPlatformMonitor()          { MainPos = MainSize = WorkPos = WorkSize = ImVec2(0, 0); DpiScale = 1.0f; PlatformHandle = NULL; }
 };
 
 // (Optional) Support for IME (Input Method Editor) via the io.SetPlatformImeDataFn() function.