diff --git a/imgui.cpp b/imgui.cpp
index 24fbb7d0..dcb7c3b7 100644
--- a/imgui.cpp
+++ b/imgui.cpp
@@ -10532,12 +10532,13 @@ static void SetWindowViewport(ImGuiWindow* window, ImGuiViewportP* viewport)
 
 static bool ImGui::GetWindowAlwaysWantOwnViewport(ImGuiWindow* window)
 {
-    // Tooltips and menus are not automatically forced into their own viewport when the NoMerge flag is set, however the multiplication of viewports makes them more likely to protude and create their own.
+    // Tooltips and menus are not automatically forced into their own viewport when the NoMerge flag is set, however the multiplication of viewports makes them more likely to protrude and create their own.
     ImGuiContext& g = *GImGui;
-    if (g.IO.ConfigViewportsNoAutoMerge && (g.ConfigFlagsForFrame & ImGuiConfigFlags_ViewportsEnable))
-        if (!window->DockIsActive)
-            if ((window->Flags & (ImGuiWindowFlags_ChildWindow | ImGuiWindowFlags_ChildMenu | ImGuiWindowFlags_Tooltip | ImGuiWindowFlags_Popup)) == 0)
-                return true;
+    if (g.IO.ConfigViewportsNoAutoMerge || ((window->WindowClass.ViewportFlagsOverrideValue & window->WindowClass.ViewportFlagsOverrideMask) & ImGuiViewportFlags_NoAutoMerge))
+        if (g.ConfigFlagsForFrame & ImGuiConfigFlags_ViewportsEnable)
+            if (!window->DockIsActive)
+                if ((window->Flags & (ImGuiWindowFlags_ChildWindow | ImGuiWindowFlags_ChildMenu | ImGuiWindowFlags_Tooltip | ImGuiWindowFlags_Popup)) == 0)
+                    return true;
     return false;
 }
 
@@ -14812,10 +14813,11 @@ void ImGui::ShowMetricsWindow(bool* p_open)
                 ImGuiWindowFlags flags = viewport->Flags;
                 ImGui::BulletText("Pos: (%.0f,%.0f), Size: (%.0f,%.0f), Monitor: %d, DpiScale: %.0f%%", viewport->Pos.x, viewport->Pos.y, viewport->Size.x, viewport->Size.y, viewport->PlatformMonitor, viewport->DpiScale * 100.0f);
                 if (viewport->Idx > 0) { ImGui::SameLine(); if (ImGui::SmallButton("Reset Pos")) { viewport->Pos = ImVec2(200,200); if (viewport->Window) viewport->Window->Pos = ImVec2(200,200); } }
-                ImGui::BulletText("Flags: 0x%04X =%s%s%s%s%s%s", viewport->Flags,
+                ImGui::BulletText("Flags: 0x%04X =%s%s%s%s%s%s%s", viewport->Flags,
                     (flags & ImGuiViewportFlags_CanHostOtherWindows) ? " CanHostOtherWindows" : "", (flags & ImGuiViewportFlags_NoDecoration) ? " NoDecoration" : "",
                     (flags & ImGuiViewportFlags_NoFocusOnAppearing)  ? " NoFocusOnAppearing"  : "", (flags & ImGuiViewportFlags_NoInputs)     ? " NoInputs"     : "",
-                    (flags & ImGuiViewportFlags_NoRendererClear)     ? " NoRendererClear"     : "", (flags & ImGuiViewportFlags_Minimized)    ? " Minimized"    : "");
+                    (flags & ImGuiViewportFlags_NoRendererClear)     ? " NoRendererClear"     : "", (flags & ImGuiViewportFlags_Minimized)    ? " Minimized"    : "",
+                    (flags & ImGuiViewportFlags_NoAutoMerge)         ? " NoAutoMerge"         : "");
                 for (int layer_i = 0; layer_i < IM_ARRAYSIZE(viewport->DrawDataBuilder.Layers); layer_i++)
                     for (int draw_list_i = 0; draw_list_i < viewport->DrawDataBuilder.Layers[layer_i].Size; draw_list_i++)
                         Funcs::NodeDrawList(NULL, viewport, viewport->DrawDataBuilder.Layers[layer_i][draw_list_i], "DrawList");
diff --git a/imgui.h b/imgui.h
index 1067787f..d9307529 100644
--- a/imgui.h
+++ b/imgui.h
@@ -1429,7 +1429,7 @@ struct ImGuiIO
     bool        ConfigDockingTransparentPayload;// = false          // [BETA] Make window or viewport transparent when docking and only display docking boxes on the target viewport. Useful if rendering of multiple viewport cannot be synced. Best used with ConfigViewportsNoAutoMerge.
     
     // Viewport options (when ImGuiConfigFlags_ViewportsEnable is set)
-    bool        ConfigViewportsNoAutoMerge;     // = false;         // Set to make all floating imgui windows always create their own viewport. Otherwise, they are merged into the main host viewports when overlapping it.
+    bool        ConfigViewportsNoAutoMerge;     // = false;         // Set to make all floating imgui windows always create their own viewport. Otherwise, they are merged into the main host viewports when overlapping it. May also set ImGuiViewportFlags_NoAutoMerge on individual viewport.
     bool        ConfigViewportsNoTaskBarIcon;   // = false          // Disable default OS task bar icon flag for secondary viewports. When a viewport doesn't want a task bar icon, ImGuiViewportFlags_NoTaskBarIcon will be set on it.
     bool        ConfigViewportsNoDecoration;    // = true           // [BETA] Disable default OS window decoration flag for secondary viewports. When a viewport doesn't want window decorations, ImGuiViewportFlags_NoDecoration will be set on it. Enabling decoration can create subsequent issues at OS levels (e.g. minimum window size).
     bool        ConfigViewportsNoDefaultParent; // = false          // Disable default OS parenting to main viewport for secondary viewports. By default, viewports are marked with ParentViewportId = <main_viewport>, expecting the platform back-end to setup a parent/child relationship between the OS windows (some back-end may ignore this). Set to true if you want the default to be 0, then all viewports will be top-level OS windows.
@@ -2383,9 +2383,10 @@ enum ImGuiViewportFlags_
     ImGuiViewportFlags_NoFocusOnClick           = 1 << 3,   // Platform Window: Don't take focus when clicked on.
     ImGuiViewportFlags_NoInputs                 = 1 << 4,   // Platform Window: Make mouse pass through so we can drag this window while peaking behind it.
     ImGuiViewportFlags_NoRendererClear          = 1 << 5,   // Platform Window: Renderer doesn't need to clear the framebuffer ahead (because we will fill it entirely).
-    ImGuiViewportFlags_TopMost                  = 1 << 6,   // Platform Window: Display on top (for tooltips only)
+    ImGuiViewportFlags_TopMost                  = 1 << 6,   // Platform Window: Display on top (for tooltips only).
     ImGuiViewportFlags_Minimized                = 1 << 7,   // Platform Window: Window is minimized, can skip render. When minimized we tend to avoid using the viewport pos/size for clipping window or testing if they are contained in the viewport.
-    ImGuiViewportFlags_CanHostOtherWindows      = 1 << 8    // Main viewport: can host multiple imgui windows (secondary viewports are associated to a single window)
+    ImGuiViewportFlags_NoAutoMerge              = 1 << 8,   // Platform Window: Avoid merging this widow into another host window. This can only be set via ImGuiWindowClass viewport flags override (because we need to now ahead if we are going to create a viewport in the first place!).
+    ImGuiViewportFlags_CanHostOtherWindows      = 1 << 9    // Main viewport: can host multiple imgui windows (secondary viewports are associated to a single window).
 };
 
 // The viewports created and managed by imgui. The role of the platform back-end is to create the platform/OS windows corresponding to each viewport.