Double-click on worksheet cell selecting item from Form Listbox

[SteveInAlabama]

When a user single-clicks a cell to Select its row, and then clicks a Command Button, I launch a Form. The form has a Listbox; the SelectionIndex for the Listbox is set via code to default to the correct corresponding item in the Listbox. For example, if the row contains the information to choose the 3rd item in the Listbox (SelectionIndex = 2), that is what is highlighted in the Listbox when the form opens. Works perfect.

I want to also allow the user to Double-click a cell in the desired row, and have the code 'Click the button' for them. However, the double-click seems to carry through to the Form and always selects the item in the Listbox 'underneath' the mouse cursor, trumping the default. From the above example, if the cursor is over item#10 when the form appears, item #10 is selected instead of item #3.

Here are snippets of my properly working code called by the button click:

Sub SelectDTReasonCode()
    Dim clsDTEvent As ClsM_DTEvent
    Dim frmReasonCodes As Frm_Reason_Codes
    Dim lThisRngRowNmbr As Long
    Dim bFailed As Boolean
  
   'class method to get info to pre-select the Listbox 
    gclsThisShift.GetEventByWksRngRowNumber lActiveCell.Row, clsDTEvent, True, bFailed

    If bFailed Then Exit Sub
    Set frmReasonCodes = New Frm_Reason_Codes
    Set frmReasonCodes.DTEvent = clsDTEvent
    frmReasonCodes.Show
    Set frmReasonCodes = Nothing
End Sub

Here is my double-click code that is (wrongly) also single-clicking on the Form's Listbox:

Private Sub Worksheet_BeforeDoubleClick(ByVal Target As Range, Cancel As Boolean)

        Cancel = True   'Deselect double-clicked cell
        SelectDTReasonCode

End Sub

Application.Undo fails, Application.SendKeys "{ESC}" did not help. I'm stuck. Any ideas?

Thanks in advance!