Private Sub L_grid1_DblClick(Cancel As Integer)
   donnee1 = Me.L_grid1.Column(0)
   donnee2 = Me.L_grid1.Column(1)
   Call OuvrirMonEtat(....)
End Sub

If the MultiSelect property is set to Simple or Extended, you can use the Selected property or the ItemsSelected collection to determine whether a particular item in the list is selected. The Selected property is a zero-based array that contains the selection state of each item in a list box. For example, if you wanted to determine whether the first item in a list box is selected, you would check the value of the Selected property for that item. The following line of code prints the value of the Selected property for the first item in a list box named List1 to the Debug window:
Debug.Print Me!List1.Selected(0)
To return data from a row in a list box, regardless of whether that row is selected, you can use either the ItemData property or the Column property. The ItemData property returns data from the column specified by the BoundColumn property. The Column property returns data from a specified row and column.