Excel-VBA: Adding a button clears the clipboard - workaround needed

Question

OK, so I have some worksheet code that detects when a cell in a range is selected and creates a button alongside it. Everything appeared to be OK, but something about creating the button clears the clipboard. Here's the original code that is called whenever a cell in the relevant range is selected:

Public Sub splitTransactionIn(ByVal Target As Range)
  Dim btn As Button
  Set t = ActiveSheet.Range("E" & Target.Row)
  rowNumber = Target.Row
  On Error Resume Next
  ActiveSheet.Buttons("Split").Delete
  Set btn = ActiveSheet.Buttons.Add(t.Left, t.Top, t.Width, t.Height)
  With btn
    .OnAction = "btnIn"
    .Caption = "Split transaction"
    .Name = "Split"
  End With
End Sub

I tried commenting sections out and inserting breakpoints, and as soon as either .OnAction, .Caption or .Name are reached, the clipboard is cleared. Why, I have no idea.

Thinking about it logically, I added in a few extra lines of code to capture the clipboard before it was cleared and replace it at the end of the sub, so I end up with this:

Public Sub splitTransactionIn(ByVal Target As Range)
  Dim btn As Button
  Dim objData As New MSForms.DataObject
  Dim strText

  objData.GetFromClipboard
  strText = objData.GetText()
  Set t = ActiveSheet.Range("E" & Target.Row)
  rowNumber = Target.Row    ' gets used elsewhere...
  On Error Resume Next
  ActiveSheet.Buttons("Split").Delete
  Set btn = ActiveSheet.Buttons.Add(t.Left, t.Top, t.Width, t.Height)
  With btn
    .OnAction = "btnIn"
    .Caption = "Split transaction"
    .Name = "Split"
  End With
  objData.SetText strText
  objData.PutInClipboard
End Sub

Now, this works, but only to a point. So I select a cell in the range and copy it (Ctrl-C), I now select (say) 3 cells further down in the same range and try to paste (Ctrl-V). What I get is an error message: "Data On Clipboard Is Not The Same Size And Shape As Selected Area" and if I hit OK, it just pastes to a single cell. I know the source and targets are different sizes, but elsewhere in the sheet this works fine when copy/pasting. Clearly I have done something odd in reading/writing the clipboard, but I have no idea what.

Answer 1

OK, so Excel really fought me every step of the way here. In essence, as has been said, any change in the interface wipes the clipboard. So in my case when I selected a target cell, my own code was inserting a new button alongside and wiping the clipboard.

Attempting to copy the clipboard as I tried in my second attempt proved to be very unreliable, for some reason. Anyway, the answer was to use a different column to trigger the button generation, so when I select a target cell for the paste, the clipboard is left intact.

As a final gotcha, be aware that sheet level code to detect when a cell is selected (which is what I was using) doesn't work if the cell is protected...