From 3d56fcd8488472911f690eaec8f127feb949e313 Mon Sep 17 00:00:00 2001
From: Chris Savoie <chris@chrissavoie.com>
Date: Thu, 4 Apr 2019 21:41:26 -0700
Subject: [PATCH] [Win32]: Always update mouse position regardless of focus.

---
 examples/imgui_impl_win32.cpp | 56 +++++++++++++++--------------------
 1 file changed, 24 insertions(+), 32 deletions(-)

diff --git a/examples/imgui_impl_win32.cpp b/examples/imgui_impl_win32.cpp
index 8a2b6771e625..014ae5c2aced 100644
--- a/examples/imgui_impl_win32.cpp
+++ b/examples/imgui_impl_win32.cpp
@@ -165,40 +165,32 @@ static void ImGui_ImplWin32_UpdateMousePos()
     POINT mouse_screen_pos;
     if (!::GetCursorPos(&mouse_screen_pos))
         return;
-    if (HWND focused_hwnd = ::GetForegroundWindow())
+
+    if (io.ConfigFlags & ImGuiConfigFlags_ViewportsEnable)
     {
-        if (::IsChild(focused_hwnd, g_hWnd))
-            focused_hwnd = g_hWnd;
-        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)
-            // This is the position you can get with GetCursorPos(). In theory adding viewport->Pos is also the reverse operation of doing ScreenToClient().
-            if (ImGui::FindViewportByPlatformHandle((void*)focused_hwnd) != NULL)
-                io.MousePos = ImVec2((float)mouse_screen_pos.x, (float)mouse_screen_pos.y);
-        }
-        else
-        {
-            // 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.)
-            // This is the position you can get with GetCursorPos() + ScreenToClient() or from WM_MOUSEMOVE.
-            if (focused_hwnd == g_hWnd)
-            {
-                POINT mouse_client_pos = mouse_screen_pos;
-                ::ScreenToClient(focused_hwnd, &mouse_client_pos);
-                io.MousePos = ImVec2((float)mouse_client_pos.x, (float)mouse_client_pos.y);
-            }
-        }
+        // 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)
+        // This is the position you can get with GetCursorPos(). In theory adding viewport->Pos is also the reverse operation of doing ScreenToClient().
+        io.MousePos = ImVec2((float)mouse_screen_pos.x, (float)mouse_screen_pos.y);
+
+		// (Optional) When using multiple viewports: set io.MouseHoveredViewport to the viewport the OS mouse cursor is hovering.
+		// Important: this information is not easy to provide and many high-level windowing library won't be able to provide it correctly, because
+		// - This is _ignoring_ viewports with the ImGuiViewportFlags_NoInputs flag (pass-through windows).
+		// - This is _regardless_ of whether another viewport is focused or being dragged from.
+		// If ImGuiBackendFlags_HasMouseHoveredViewport is not set by the back-end, imgui will ignore this field and infer the information by relying on the
+		// rectangles and last focused time of every viewports it knows about. It will be unaware of foreign windows that may be sitting between or over your windows.
+		if (HWND hovered_hwnd = ::WindowFromPoint(mouse_screen_pos))
+			if (ImGuiViewport* viewport = ImGui::FindViewportByPlatformHandle((void*)hovered_hwnd))
+				if ((viewport->Flags & ImGuiViewportFlags_NoInputs) == 0) // FIXME: We still get our NoInputs window with WM_NCHITTEST/HTTRANSPARENT code when decorated?
+					io.MouseHoveredViewport = viewport->ID;
+	}
+    else
+    {
+        // 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.)
+        // This is the position you can get with GetCursorPos() + ScreenToClient() or from WM_MOUSEMOVE.
+        POINT mouse_client_pos = mouse_screen_pos;
+        ::ScreenToClient(g_hWnd, &mouse_client_pos);
+        io.MousePos = ImVec2((float)mouse_client_pos.x, (float)mouse_client_pos.y);
     }
-
-    // (Optional) When using multiple viewports: set io.MouseHoveredViewport to the viewport the OS mouse cursor is hovering.
-    // Important: this information is not easy to provide and many high-level windowing library won't be able to provide it correctly, because
-    // - This is _ignoring_ viewports with the ImGuiViewportFlags_NoInputs flag (pass-through windows).
-    // - This is _regardless_ of whether another viewport is focused or being dragged from.
-    // If ImGuiBackendFlags_HasMouseHoveredViewport is not set by the back-end, imgui will ignore this field and infer the information by relying on the
-    // rectangles and last focused time of every viewports it knows about. It will be unaware of foreign windows that may be sitting between or over your windows.
-    if (HWND hovered_hwnd = ::WindowFromPoint(mouse_screen_pos))
-        if (ImGuiViewport* viewport = ImGui::FindViewportByPlatformHandle((void*)hovered_hwnd))
-            if ((viewport->Flags & ImGuiViewportFlags_NoInputs) == 0) // FIXME: We still get our NoInputs window with WM_NCHITTEST/HTTRANSPARENT code when decorated?
-                io.MouseHoveredViewport = viewport->ID;
 }
 
 #ifdef _MSC_VER