listview line selection

[RhinoBull]

1. assume i have 255 items in listbox1 and i wanna move 20 items in to

Sample below will "move" last 20 items from list1 to list2 every 1 second until list1 is empty:

Option Explicit

Private Sub Form_Load()
Dim i As Integer

    For i = 1 To 255
        List1.AddItem "Item " & i
    Next i
    Timer1.Enabled = False
    Timer1.Interval = 1000 '1 second

End Sub

Private Sub Command1_Click()
    Timer1.Enabled = True
End Sub

Private Sub Timer1_Timer()
Dim i As Integer
Dim sItem As String

    For i = List1.ListCount - 1 To List1.ListCount - 20 Step -1
        If i < 0 Then Exit For
        sItem = List1.List(i)
        List2.AddItem sItem, 0
        List1.RemoveItem (i)
    Next i
    
    Timer1.Enabled = CBool(List1.ListCount)

End Sub

If you want to move first items instead then you need to modify loop a bit (timer1_timer procedure).