How can the sub below be modified to a sheet level code that works like the
pop-up DV input message (ie when DV cell is selected, the input message will
show)? Or any other sub which can give the same functionality - when cell
(within a defined range on the sheet) is selected, show the shape "txt1",
when cell is deselected, hide the shape? Thanks

Sub T_Box1()
If ActiveSheet.Shapes("txt1").Visible = False Then
ActiveSheet.Shapes("txt1").Visible = True
Else
ActiveSheet.Shapes("txt1").Visible = False
End If
End Sub