DragEvent 构造函数

 CONSTRUCTOR(
	_hWnd,
	_uMsg,
	_wParam,
	_lParam,
	_oWindow
) CLIPPER

[ClipperCallingConventionAttribute(new string[] { ... })]
public DragEvent(
	__Usual _hWnd = default,
	__Usual _uMsg = default,
	__Usual _wParam = default,
	__Usual _lParam = default,
	__Usual _oWindow = default
)