急！实现类似windows鼠标选择多个文件的功能！
简单的说就是鼠标左键先按下，然后移动鼠标，就会出现一个矩形的以选择范围，就像windows里的操作一样，现在我已经基本可以实现这个功能，就是用GDI+画的那个矩形的边框一直在闪，我已经用了如双缓冲等技术，但还是闪的利害，请各位高手帮帮忙！
基本代码如下：

bool isChoose;
int mouseX;
int mouseY;
Graphics myGraphics;
Image bitmap;
public FrmAG()
{
InitializeComponent();
bitmap = new Bitmap(this.Width, this.Height);
myGraphics = Graphics.FromImage(bitmap);
this.DoubleBuffered = true;
SetStyle(ControlStyles.ResizeRedraw, true);
}
private void FrmAG_MouseDown(object sender, MouseEventArgs e)
{
if (e.Button == MouseButtons.Left)
{
isChoose = true;
mouseX = e.X;
mouseY = e.Y;
}
}

private void FrmAG_MouseUp(object sender, MouseEventArgs e)
{
if (e.Button == MouseButtons.Left)
{
isChoose = false;
Invalidate();
}
}

private void FrmAG_MouseMove(object sender, MouseEventArgs e)
{
if (isChoose)
{

myGraphics.DrawRectangle(new Pen(Color.Blue, 2), lastX, lastY, lastWidth, lastHeight);
myGraphics.Clear(Color.Empty);

int width;
int height;
int x;
int y;

if (mouseX < e.X)
{
x = mouseX;
width = e.X - mouseX;
}
else
{
x = e.X;
width = mouseX - e.X;
}

if (mouseY < e.Y)
{
y = mouseY;
height = e.Y - mouseY;
}
else
{
y = e.Y;
height = mouseY - e.Y;

}

lastHeight = height;
lastWidth = width;
lastX = x;
lastY = y;

myGraphics.DrawRectangle(new Pen(Color.Blue, 2), x, y, width, height);
this.Invalidate();
}
}

private void FrmAG_Paint(object sender, PaintEventArgs e)
{
if (isChoose == true)
{
Graphics graphics = this.CreateGraphics();
graphics.DrawImage(bitmap, 0, 0);
}
}

不管大家用gdi+、gdi或者api等什么技术都可以，只要能实现功能就好了，请大家多多指点！


[解决办法]
参考下这个代码(可以把代码直接放到一个Form上运行看效果)：

private Point m_LastPoint;
private Point m_StartPoint;
protected override void OnMouseDown(MouseEventArgs e)
{
base.OnMouseDown(e);
this.m_StartPoint = e.Location;
this.m_LastPoint = this.m_StartPoint;
}
protected override void OnMouseMove(MouseEventArgs e)
{
base.OnMouseMove(e);
if (this.Capture)
{
Rectangle oldRect = Rectangle.FromLTRB(m_StartPoint.X, m_StartPoint.Y, this.m_LastPoint.X, this.m_LastPoint.Y);
oldRect = this.RectangleToScreen(oldRect);
ControlPaint.DrawReversibleFrame(oldRect, Color.Black, FrameStyle.Dashed);

Rectangle rect = Rectangle.FromLTRB(m_StartPoint.X, m_StartPoint.Y, e.X, e.Y);
rect = this.RectangleToScreen(rect);
ControlPaint.DrawReversibleFrame(rect, Color.Black, FrameStyle.Dashed);
this.m_LastPoint = e.Location;
}
}
protected override void OnMouseUp(MouseEventArgs e)
{
base.OnMouseUp(e);
Rectangle oldRect = Rectangle.FromLTRB(m_StartPoint.X, m_StartPoint.Y, this.m_LastPoint.X, this.m_LastPoint.Y);
oldRect = this.RectangleToScreen(oldRect);
ControlPaint.DrawReversibleFrame(oldRect, Color.Black, FrameStyle.Dashed);
}