无法修改“System.Collections.Generic.List<System.Drawing.Rectangle>.this[int]”的返回值，
因为它不是变量
部分源码如下：
private List<RectangleEx> CRectLst = new List<RectangleEx>();
private List<Rectangle> RectLst = new List<Rectangle>();
其中RectangleEx为我自定义的类：
public class RectangleEx
{
private Rectangle rect;
public Rectangle Rect
{
get
{
return this.rect;
}
set
{
this.rect = value;
}
}
public int X
{
get
{
return this.rect.X;
}
set
{
this.rect.X = value;
}
}
public int Y
{
get
{
return this.rect.Y;
}
set
{
this.rect.Y = value;
}
}
public int Width
{
get
{
return this.rect.Width;
}
set
{
this.rect.Width = value;
}
}
public int Height
{
get
{
return this.rect.Height;
}
set
{
this.rect.Height = value;
}
}
public int Left
{
get
{
return this.rect.Left;
}
}
public int Right