Public Class Form1
　Inherits System.Windows.Forms.Form

　Private mouse_offset As Point
　Private Sub form1_MouseDown(ByVal sender As Object, ByVal e As 　System.Windows.Forms.MouseEventArgs) Handles MyBase.MouseDown
　　mouse_offset = New Point(e.X, e.Y)
　End Sub

Private Sub form1_MouseMove(ByVal Sender As System.Object, ByVal e As System.Windows.Forms.MouseEventArgs) Handles MyBase.MouseMove
　’按住鼠标左右键均可拖动窗体
　If e.Button = MouseButtons.Left Or e.Button = MouseButtons.Right Then
　　Dim mousePos As Point = Sender.findform().MousePosition 这段虽知道定义了一个点，但后面的代码不清楚
　　’获得鼠标偏移量
　　mousePos.Offset(-mouse_offset.X, -mouse_offset.Y)' ‘这个鼠标的偏移量是怎么会事啊？而切前面还有个负号，不懂啊
　　’设置窗体随鼠标一起移动
　　Sender.findform().Location = mousePos'这段望高手也解释一下嘛
　End If
End Sub

Private Sub BtnExit_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
　’关闭窗体
　Me.Close()
End Sub
End Class

.NET Framework 类库
Control.FindForm 方法
检索控件所在的窗体。

命名空间:System.Windows.Forms
程序集:System.Windows.Forms（在 system.windows.forms.dll 中）

语法

Visual Basic（声明）
Public Function FindForm As Form

Visual Basic（用法）
Dim instance As Control
Dim returnValue As Form

returnValue = instance.FindForm

C#
public Form FindForm ()

C++
public:
Form^ FindForm ()

J#
public Form FindForm ()

JScript
public function FindForm () : Form

返回值
控件所在的 Form。
备注

控件的 Parent 属性值可能与 FindForm 方法返回的 Form 不同。例如，如果 RadioButton 控件包含在 GroupBox 控件中，而 GroupBox 在 Form 上，RadioButton 控件的 Parent 是 GroupBox，GroupBox 控件的 Parent 是 Form。

示例

下面的代码示例查找包含指定按钮的窗体。

Visual Basic 复制代码
' This example uses the Parent property and the Find method of Control to set
' properties on the parent control of a Button and its Form. The example assumes
' that a Button control named button1 is located within a GroupBox control. The
' example also assumes that the Click event of the Button control is connected to
' the event handler method defined in the example.
Private Sub button1_Click(sender As Object, e As System.EventArgs) Handles button1.Click
' Get the control the Button control is located in. In this case a GroupBox.
Dim control As Control = button1.Parent
' Set the text and backcolor of the parent control.
control.Text = "My Groupbox"
control.BackColor = Color.Blue
' Get the form that the Button control is contained within.
Dim myForm As Form = button1.FindForm()
' Set the text and color of the form containing the Button.
myForm.Text = "The Form of My Control"
myForm.BackColor = Color.Red
End Sub

C# 复制代码
// This example uses the Parent property and the Find method of Control to set
// properties on the parent control of a Button and its Form. The example assumes
// that a Button control named button1 is located within a GroupBox control. The
// example also assumes that the Click event of the Button control is connected to
// the event handler method defined in the example.
private void button1_Click(object sender, System.EventArgs e)
{
// Get the control the Button control is located in. In this case a GroupBox.
Control control = button1.Parent;
// Set the text and backcolor of the parent control.
control.Text = "My Groupbox";
control.BackColor = Color.Blue;
// Get the form that the Button control is contained within.
Form myForm = button1.FindForm();
// Set the text and color of the form containing the Button.
myForm.Text = "The Form of My Control";
myForm.BackColor = Color.Red;
}

C++ 复制代码
// This example uses the Parent property and the Find method of Control to set
// properties on the parent control of a Button and its Form. The example assumes
// that a Button control named button1 is located within a GroupBox control. The
// example also assumes that the Click event of the Button control is connected to
// the event handler method defined in the example.
private:
void button1_Click( Object^ /*sender*/, System::EventArgs^ /*e*/ )
{
// Get the control the Button control is located in. In this case a GroupBox.
Control^ control = button1->Parent;

// Set the text and backcolor of the parent control.
control->Text = "My Groupbox";
control->BackColor = Color::Blue;

// Get the form that the Button control is contained within.
Form^ myForm = button1->FindForm();

// Set the text and color of the form containing the Button.
myForm->Text = "The Form of My Control";
myForm->BackColor = Color::Red;
}

J# 复制代码
// This example uses the Parent property and the Find method of Control to
// set properties on the parent control of a Button and its Form. The
// example assumes that a Button control named button1 is located within a
// GroupBox control. The example also assumes that the Click event of the
// Button control is connected to the event handler method defined in the
// example.
private void button1_Click(Object sender, System.EventArgs e)
{
// Get the control the Button control is located in.
// In this case a GroupBox.
Control control = button1.get_Parent();

// Set the text and backcolor of the parent control.
control.set_Text("My Groupbox");
control.set_BackColor(Color.get_Blue());

// Get the form that the Button control is contained within.
Form myForm = button1.FindForm();

// Set the text and color of the form containing the Button.
myForm.set_Text("The Form of My Control");
myForm.set_BackColor(Color.get_Red());
} //button1_Click

你查找 Sender 的用法不就行了??