サンプル(長いですが)
新しいプロジェクト→クラスライブラリ→プロジェクト→ユーザーコントロールの追加
UserControl1の上にPictureBoxを8個配置。

Imports System.Drawing

Imports System.Windows.Forms



Public Class UserControl1

    Private MousePoint As Point



    Private Sub FCHandle_UC_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load

        Call CtrlSyoki()

    End Sub



    Private Sub CtrlSyoki()

        Me.BackColor = Color.Black

        For Each c As Control In Me.Controls

            If 0 < InStr(c.Name, "PictureBox") Then

                c.Width = 10 : c.Height = 10 : c.BackColor = Color.Yellow

            End If

        Next



        With PictureBox1

            .Left = 0 : .Top = 0

        End With

        With PictureBox2

            .Left = Me.Width / 2 - .Width / 2 : .Top = 0

        End With

        With PictureBox3

            .Left = Me.Width - .Width : .Top = 0

        End With



        With PictureBox4

            .Left = 0 : .Top = Me.Height / 2 - .Height / 2

        End With

        With PictureBox5

            .Left = Me.Width - .Width : .Top = Me.Height / 2 - .Height / 2

        End With



        With PictureBox6

            .Left = 0 : .Top = Me.Height - .Height

        End With

        With PictureBox7

            .Left = Me.Width / 2 - .Width / 2 : .Top = Me.Height - .Height

        End With

        With PictureBox8

            .Left = Me.Width - .Width : .Top = Me.Height - .Height

        End With

    End Sub



    Private Sub PictureBox1_MouseDown(ByVal sender As Object, ByVal e As System.Windows.Forms.MouseEventArgs) Handles _

                    PictureBox1.MouseDown, PictureBox2.MouseDown, PictureBox3.MouseDown, PictureBox4.MouseDown, _

                     PictureBox5.MouseDown, PictureBox6.MouseDown, PictureBox7.MouseDown, PictureBox8.MouseDown

        If e.Button = Windows.Forms.MouseButtons.Left Then

            MousePoint = New Point(e.X, e.Y) : Call HandleHide(True)

        End If

    End Sub



    Private Sub PictureBox1_MouseMove(ByVal sender As Object, ByVal e As System.Windows.Forms.MouseEventArgs) Handles _

                    PictureBox1.MouseMove, PictureBox2.MouseMove, PictureBox3.MouseMove, PictureBox4.MouseMove, _

                     PictureBox5.MouseMove, PictureBox6.MouseMove, PictureBox7.MouseMove, PictureBox8.MouseMove

        If e.Button = Windows.Forms.MouseButtons.Left Then

            sender.left += e.X - MousePoint.X : sender.top += e.Y - MousePoint.Y

            Select Case sender.name

                Case "PictureBox1"



                Case "PictureBox2"



                Case "PictureBox3"



                Case "PictureBox4"



                Case "PictureBox5"

                    Me.Width = sender.left + sender.width

                Case "PictureBox6"



                Case "PictureBox7"

                    Me.Height = sender.top + sender.height

                Case "PictureBox8"

                    Me.Width = sender.left + sender.width : Me.Height = sender.top + sender.height

            End Select

            Me.Refresh()

        End If

    End Sub



    Private Sub PictureBox1_MouseUp(ByVal sender As Object, ByVal e As System.Windows.Forms.MouseEventArgs) Handles _

                    PictureBox1.MouseUp, PictureBox2.MouseUp, PictureBox3.MouseUp, PictureBox4.MouseUp, _

                     PictureBox5.MouseUp, PictureBox6.MouseUp, PictureBox7.MouseUp, PictureBox8.MouseUp

        Call HandleHide(False) : Call CtrlSyoki()

    End Sub



    Private Sub HandleHide(ByVal TF As Boolean)

        For Each c As Control In Me.Controls

            If 0 < InStr(c.Name, "PictureBox") Then

                c.Visible = Not TF

            End If

        Next

    End Sub

End Class