Hello I am creating an app in win32 that will display the x, y position(In screen coords) of the mouse whereever the mouse is (inside my app client/NC area & outside). I am at the stage where I want to detect when the mouse leaves my application completely. I have written a simple win32 app that should detect & notify myself when the mouse leaves my app, BUT its not working, I never receive the messages WM_MOUSELEAVE & WM_NCMOUSELEAVE. What do you think is wrong? Am I using the wrong win32 functions? // Track Mouse.cpp : Defines the entry point for the application. // #include "stdafx.h" #include <windows.h> #include <vector> #include <string> #include <cstdlib> static HINSTANCE gInstance; // Globals // enum MouseStatus { DEFAULT = 50001, LEFT_CLIENT, LEFT_NCLIENT }; static MouseStatus mouseState = DEFAULT; static COLORREF bkCol = RGB(0,255,255); // Functions List // BOOL TrackMouse( HWND hwnd ) { // Post: TRACKMOUSEEVENT mouseEvt; ZeroMemory( &mouseEvt, sizeof(TRACKMOUSEEVENT) ); mouseEvt.cbSize = sizeof(TRACKMOUSEEVENT); mouseEvt.dwFlags = TME_LEAVE | TME_NONCLIENT; //mouseEvt.dwHoverTime = HOVER_DEFAULT; mouseEvt.hwndTrack = hwnd; return TrackMouseEvent( &mouseEvt ); } LRESULT CALLBACK WndProc(HWND hwnd, UINT msg, WPARAM wParam, LPARAM lParam) { switch(msg) { case WM_CREATE: { // Track mouse so I can be notified when it leaves my application (Client & NC areas) BOOL trackSuccess = TrackMouse( hwnd ); // Returns successful, so I correctly track the mouse if ( trackSuccess == 0 ) { MessageBoxW( hwnd, L"Failed to track mouse", L"Error", MB_OK|MB_ICONEXCLAMATION ); } else MessageBoxW( hwnd, L"Tracking mouse", L"Success", MB_OK|MB_ICONEXCLAMATION ); } break; case WM_MOUSELEAVE: { // I never receive this message // Detect when the mouse leaves the client area mouseState = LEFT_CLIENT; bkCol = RGB(50,50,50); InvalidateRect( hwnd, NULL, true ); } break; case WM_NCMOUSELEAVE : { // I never receive this message // If the mouse has left the client area & then leaves the NC area then I know // that the mouse has left my app if ( mouseState == LEFT_CLIENT ) { mouseState = LEFT_NCLIENT; BOOL trackSuccess = TrackMouse( hwnd ); if ( trackSuccess == 0 ) { bkCol = RGB(255,255,0); MessageBoxW( hwnd, L"On WM_NCMOUSELEAVE: Failed to track mouse", L"Error", MB_OK|MB_ICONEXCLAMATION ); } else MessageBoxW( hwnd, L"On WM_NCMOUSELEAVE: Tracking mouse", L"Success", MB_OK|MB_ICONEXCLAMATION ); InvalidateRect( hwnd, NULL, true ); } } break; case WM_ACTIVATE: case WM_MOUSEHOVER: { // The mouse is back in my app mouseState = DEFAULT; bkCol = RGB(0,255,255); InvalidateRect( hwnd, NULL, true ); } break; case WM_PAINT: { HDC hdc; PAINTSTRUCT ps; hdc = BeginPaint( hwnd, &ps ); SetBkColor( hdc, bkCol ); Rectangle( hdc, 10, 10, 200, 200 ); EndPaint( hwnd, &ps ); } break; case WM_CLOSE: DestroyWindow(hwnd); break; case WM_DESTROY: PostQuitMessage(0); break; default: break; } return DefWindowProc(hwnd, msg, wParam, lParam); } int WINAPI WinMain(HINSTANCE gInstance, HINSTANCE hPrevInstance, LPSTR lpCmdLine, int nCmdShow) { WNDCLASSEX wc; HWND hwnd; MSG Msg; wc.cbSize = sizeof(WNDCLASSEX); wc.style = 0; wc.lpfnWndProc = WndProc; wc.cbClsExtra = 0; wc.cbWndExtra = 0; wc.hInstance = gInstance; wc.hIcon = LoadIcon(NULL, IDI_APPLICATION); wc.hCursor = LoadCursor(NULL, IDC_ARROW); wc.hbrBackground = (HBRUSH)(DKGRAY_BRUSH); wc.lpszMenuName = NULL; wc.lpszClassName = L"Custom Class"; wc.hIconSm = LoadIcon(NULL, IDI_APPLICATION); // if registration of main class fails if(!RegisterClassEx(&wc)) { MessageBoxW(NULL, L"Window Registration Failed!", L"Error!", MB_ICONEXCLAMATION | MB_OK); return 0; } hwnd = CreateWindowEx( WS_EX_CLIENTEDGE, L"Custom Class", L"App Name", WS_CAPTION|WS_MINIMIZEBOX|WS_VISIBLE|WS_OVERLAPPED|WS_SYSMENU, CW_USEDEFAULT, CW_USEDEFAULT, 600, 500, NULL, NULL, gInstance, NULL); if(hwnd == NULL) { MessageBoxW(NULL, L"Window Creation Failed!", L"Error!", MB_ICONEXCLAMATION | MB_OK); return 0; } ShowWindow(hwnd, nCmdShow); UpdateWindow(hwnd); while(GetMessage(&Msg, NULL, 0, 0) > 0) { TranslateMessage(&Msg); DispatchMessage(&Msg); } return Msg.wParam; }