diff --git a/src/event/Input.cpp b/src/event/Input.cpp
index 5b6b770..4bed454 100644
--- a/src/event/Input.cpp
+++ b/src/event/Input.cpp
@@ -51,6 +51,7 @@ int32_t Input::s_simulatedRightButtonClick;
 uint32_t Input::s_metaKeyState;
 int32_t Input::s_queueHead;
 int32_t Input::s_queueTail;
+int32_t Input::s_windowFocused;
 
 #if defined(WHOA_SYSTEM_WIN)
     int32_t Input::s_savedMouseSpeed;
diff --git a/src/event/Input.hpp b/src/event/Input.hpp
index 2c8c04c..36f855f 100644
--- a/src/event/Input.hpp
+++ b/src/event/Input.hpp
@@ -21,6 +21,7 @@ namespace Input {
     extern uint32_t s_metaKeyState;
     extern int32_t s_queueHead;
     extern int32_t s_queueTail;
+    extern int32_t s_windowFocused;
 
     #if defined(WHOA_SYSTEM_WIN)
         extern int32_t s_savedMouseSpeed;
diff --git a/src/event/win/Window.cpp b/src/event/win/Window.cpp
index cd6a1cd..2174cd4 100644
--- a/src/event/win/Window.cpp
+++ b/src/event/win/Window.cpp
@@ -8,11 +8,27 @@ int32_t OsGuiProcessMessage(void* message) {
 }
 
 int32_t OsWindowProc(void* window, uint32_t message, uintptr_t wparam, intptr_t lparam) {
+    auto hwnd = static_cast<HWND>(window);
+
     // TODO
 
     switch (message) {
     // TODO handle remaining message types
 
+    case WM_ACTIVATE: {
+        auto isMinimized = IsIconic(hwnd);
+        auto isActive = wparam != WA_INACTIVE;
+        Input::s_windowFocused = isActive && !isMinimized;
+
+        // TODO capture
+
+        // TODO mouse speed
+
+        OsQueuePut(OS_INPUT_FOCUS, Input::s_windowFocused != 0, 0, 0, 0);
+
+        break;
+    }
+
     case WM_CLOSE: {
         OsQueuePut(OS_INPUT_CLOSE, 0, 0, 0, 0);
         return 0;