Sup guys,

In the following code the program should simply make a cross over any window clicked, although it does that there is a slight problem; the lines start at the correct corners of the client area but end at the wrong and also the beggining positions are also wrong when the window is not maximised.

#include <windows>

const char *ClsName = "BasicApp";
const char *WndName = "Pro Painter Deluxe - Matahir Shah";

LRESULT CALLBACK WndProc(HWND hWnd, UINT uMsg,
WPARAM wParam, LPARAM lParam);

HINSTANCE hInstance;

int WINAPI WinMain(HINSTANCE hInstance, HINSTANCE hPrevInstance,
LPSTR lpCmdLine, int nCmdShow)
{
MSG Msg;
HWND hWnd;
WNDCLASSEX WndClsEx;

// Create the application window
WndClsEx.cbSize = sizeof(WNDCLASSEX);
WndClsEx.style = CS_HREDRAW | CS_VREDRAW;
WndClsEx.lpfnWndProc = WndProc;
WndClsEx.cbClsExtra = 0;
WndClsEx.cbWndExtra = 0;
WndClsEx.hIcon = LoadIcon(NULL, IDI_APPLICATION);
WndClsEx.hCursor = LoadCursor(NULL, IDC_ARROW);
WndClsEx.hbrBackground = (HBRUSH)GetStockObject(WHITE_BRUSH);
WndClsEx.lpszMenuName = NULL;
WndClsEx.lpszClassName = ClsName;
WndClsEx.hInstance = hInstance;
WndClsEx.hIconSm = LoadIcon(NULL, IDI_APPLICATION);

// Register the application
RegisterClassEx(&WndClsEx);

// Create the window object
hWnd = CreateWindowEx(NULL,
ClsName,
WndName,
WS_OVERLAPPEDWINDOW,
CW_USEDEFAULT,
CW_USEDEFAULT,
CW_USEDEFAULT,
CW_USEDEFAULT,
NULL,
NULL,
hInstance,
NULL);

// Find out if the window was created
if( !hWnd ) // If the window was not created,
return 0; // stop the application

// Display the window to the user
ShowWindow(hWnd, SW_SHOWNORMAL);
UpdateWindow(hWnd);

// Decode and treat the messages
// as long as the application is running
while( GetMessage(&Msg, NULL, 0, 0) )
{
TranslateMessage(&Msg);
DispatchMessage(&Msg);
}

return Msg.wParam;
}

LRESULT CALLBACK WndProc(HWND hWnd, UINT Msg, WPARAM wParam, LPARAM lParam)
{

switch (Msg)
{

case WM_LBUTTONDOWN :

POINT AreaClicked;
HWND WindowHandle;
HDC DC;
RECT WindowPosition;

GetCursorPos(&AreaClicked);
ScreenToClient(hWnd, &AreaClicked);
WindowHandle = WindowFromPoint(AreaClicked);
GetWindowRect(WindowHandle, &WindowPosition);

DC = GetDC(WindowHandle);
LineTo(DC, WindowPosition.right, WindowPosition.bottom);
MoveToEx(DC, WindowPosition.right, WindowPosition.top, NULL);
LineTo(DC, WindowPosition.left, WindowPosition.bottom);
ReleaseDC(WindowHandle, DC);

break;

case WM_DESTROY :

InvalidateRect(NULL, NULL, NULL);
PostQuitMessage(0);

break;

}

I know there are many problems in the code but it is because I still don't know how to work with total mouse control, if you know please reply to the thread known as "Mouse Power".

Thanks.