POINT结构是在哪个文件中定义的？
typedef struct tagPOINT
{
LONG x;
LONG y;
} POINT;

在很多文件中用到这个结构，但我找不到出处。

[解决办法]
windef.h
[解决办法]
LZ要学会查MSDN：
============================

POINT
The POINT structure defines the x- and y- coordinates of a point.

typedef struct tagPOINT {
LONG x;
LONG y;
} POINT, *PPOINT;
Members
x
Specifies the x-coordinate of the point.
y
Specifies the y-coordinate of the point.
Requirements
Windows NT/2000: Requires Windows NT 3.1 or later.
Windows 95/98: Requires Windows 95 or later.
Header: Declared in Windef.h; include Windows.h.