LRESULT CALLBACK WndProc (HWND hWnd, UINT msg, WPARAM wp, LPARAM lp)
{
static HDC hdc[2], hmdc[2];
static HBITMAP hbmp = NULL;
HBITMAP pre;
static RECT rc;
POINT p;

switch (msg) {
case WM_CREATE:
	hdc[0] = GetDC(hWnd);
	hdc[1] = GetDC(NULL);
	hmdc[0] = CreateCompatibleDC(hdc[0]);
	hmdc[1] = CreateCompatibleDC(hdc[1]);
	SetWindowLong(hWnd, GWL_EXSTYLE, GetWindowLong(hWnd, GWL_EXSTYLE)|WS_EX_LAYERED);
	SetLayeredWindowAttributes(hWnd, 0, 0xFF, LWA_ALPHA);
	break;

case WM_LBUTTONDOWN:
	GetClientRect(hWnd, &rc);
	p.x = rc.left;
	p.y = rc.top;
	ClientToScreen(hWnd, &p);

	SetLayeredWindowAttributes(hWnd, 0, 0x00, LWA_ALPHA);

	if (hbmp!=NULL) {
		SelectObject(hmdc[1], pre);
		DeleteObject(hbmp);
		}
	hbmp = CreateCompatibleBitmap(hdc[1], rc.right, rc.bottom);
	pre = (HBITMAP)SelectObject(hmdc[1], hbmp);
	BitBlt(hmdc[1], 0, 0, rc.right, rc.bottom, hdc[1], p.x, p.y, SRCCOPY);
	SelectObject(hmdc[1], pre);
	SelectObject(hmdc[0], hbmp);

	SetLayeredWindowAttributes(hWnd, 0, 0xFF, LWA_ALPHA);
	InvalidateRect(hWnd, NULL, FALSE);
	break;

case WM_PAINT:
	if (hbmp!=NULL) BitBlt(hdc[0], 0, 0, rc.right, rc.bottom, hmdc[0], 0, 0, SRCCOPY);
	break;

case WM_CLOSE:
	DeleteObject(hbmp);
	SelectObject(hmdc[0], pre);
	DeleteDC(hmdc[1]);
	DeleteDC(hmdc[0]);
	ReleaseDC(NULL, hdc[1]);
	ReleaseDC(hWnd, hdc[0]);
	DestroyWindow(hWnd);
	break;

case WM_DESTROY:
	PostQuitMessage(0);
	return 0;
	}

return DefWindowProc(hWnd, msg, wp, lp);
}