Public Sub SplitWindow()
    Dim freezeMode, win As Window
    If TypeName(ActiveSheet) <> "Worksheet" Then Exit Sub
    Set win = ActiveWindow
    freezeMode = win.FreezePanes
    win.FreezePanes = False' else the split cannot be changed
    If win.Split Then win.Split = False: Exit Sub' cancel split
    win.SplitRow = ActiveCell.Row - win.ScrollRow
    win.SplitColumn = ActiveCell.Column - win.ScrollColumn
    win.FreezePanes = freezeMode' restore split
End Sub

' To reverse the process

Public Sub UnSplitWindow()
    With ActiveWindow
        .SplitColumn = 0
        .SplitRow = 0
    End With
End Sub