Backends: SDL2, SDL3, Win32: don't submit monitor with 0 DpiScale (e.g. accessibility virtual monitor?). to prevent assert. (#7902)

I am not too confident on this but I believe pushing this is the fastest way we will get feedback.

backends/imgui_impl_glfw.cpp

@@ -907,7 +907,7 @@ static void ImGui_ImplGlfw_UpdateMonitors()
         float x_scale, y_scale;
         glfwGetMonitorContentScale(glfw_monitors[n], &x_scale, &y_scale);
         if (x_scale == 0.0f)
-            continue; // Some accessibility applications are declaring fake monitors with a DPI of 0, see (#7902)
+            continue; // Some accessibility applications are declaring virtual monitors with a DPI of 0, see #7902.
         monitor.DpiScale = x_scale;
 #endif
         monitor.PlatformHandle = (void*)glfw_monitors[n]; // [...] GLFW doc states: "guaranteed to be valid only until the monitor configuration changes"

backends/imgui_impl_sdl2.cpp

@@ -848,7 +848,11 @@ static void ImGui_ImplSDL2_UpdateMonitors()
         //  DpiScale to cocoa_window.backingScaleFactor here.
         float dpi = 0.0f;
         if (!SDL_GetDisplayDPI(n, &dpi, nullptr, nullptr))
+        {
+            if (dpi <= 0.0f)
+                continue; // Some accessibility applications are declaring virtual monitors with a DPI of 0, see #7902.
             monitor.DpiScale = dpi / 96.0f;
+        }
 #endif
         monitor.PlatformHandle = (void*)(intptr_t)n;
         platform_io.Monitors.push_back(monitor);

backends/imgui_impl_sdl3.cpp

@@ -806,6 +806,8 @@ static void ImGui_ImplSDL3_UpdateMonitors()
         //  DpiScale to cocoa_window.backingScaleFactor here.
         monitor.DpiScale = SDL_GetDisplayContentScale(display_id);
         monitor.PlatformHandle = (void*)(intptr_t)n;
+        if (monitor.DpiScale <= 0.0f)
+            continue; // Some accessibility applications are declaring virtual monitors with a DPI of 0, see #7902.
         platform_io.Monitors.push_back(monitor);
     }
 }

backends/imgui_impl_win32.cpp

@@ -437,6 +437,8 @@ static BOOL CALLBACK ImGui_ImplWin32_UpdateMonitors_EnumFunc(HMONITOR monitor, H
     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;
+    if (imgui_monitor.DpiScale <= 0.0f)
+        return TRUE; // Some accessibility applications are declaring virtual monitors with a DPI of 0, see #7902.
     ImGuiPlatformIO& io = ImGui::GetPlatformIO();
     if (info.dwFlags & MONITORINFOF_PRIMARY)
         io.Monitors.push_front(imgui_monitor);

docs/CHANGELOG.txt

@@ -56,8 +56,8 @@ Docking+Viewports Branch:
 
 - Viewports: added optional platform_io.Platform_GetWindowWorkAreaInsets() hook
   to allow backends to alter the default per-viewport work-area. (#7823)
-- Backends: don't report monitors with DpiScale of 0, which seemed to be reported
+- Backends: don't report monitors with DpiScale of 0, which seemed to be reported for
-  for virtual monitors instead by accessibility drivers. (#7902) [@nicolasnoble]
+  virtual monitors instead by accessibility drivers. (#7902) [@nicolasnoble, @ocornut]
 - Backends: SDL2, SDL3: using SDL_HINT_WINDOW_NO_ACTIVATION_WHEN_SHOWN to support the
   ImGuiViewportFlags_NoFocusOnAppearing flag, instead of using a Win32-specific hack.
   (#7896) [@RT2Code]