ИнтеллигенцияX

Пример, как растягивать форму за какой-либо объект. Добавляем Label, пришвартовываем его к нижнему правовому углу.

Public Class Form1
    Dim pt As Point
    Private Sub Label1_MouseDown(ByVal sender As Object, ByVal e As System.Windows.Forms.MouseEventArgs) Handles Label1.MouseDown
        pt = New Point(e.X, e.Y)
    End Sub
    Private Sub Label1_MouseMove(ByVal sender As Object, ByVal e As System.Windows.Forms.MouseEventArgs) Handles Label1.MouseMove
        If e.Button = MouseButtons.Left Then
            Size = New Size(Width + (e.X - pt.X), Height + (e.Y - pt.Y))
        End If
    End Sub
    Private Sub Form1_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
        FormBorderStyle = FormBorderStyle.None
        Label1.Anchor = AnchorStyles.Bottom Or AnchorStyles.Right
    End Sub
End Class

Растягиваем форму C#