Selection change event on text inside a textbox

Hello,
This is the first question I post. I have been using the Excel Forum for quite a while now and it has been extremely useful so far for finding answers in older threads so thank you everybody However this time I can’t find anything so I though I’ll ask the question.

As part of a program I’m writing in VBA (for Excel 2010), I have a textbox in a user form used as an interface to write a formula in cells in Excel.
The resulting value of a formula from a cell is loaded up into the textbox. It would be shown in the textbox like “See 1.2 and 1.3” where the formula in the cell is

=”See “ & CellAddress1.value & “ and “ & CellAddress2.value

This is just used as an example but the principle is there.
It is worth noting that I’m writing this for very inexperienced Excel users but I need them to be able to edit the string part of the formula without breaking the formula.

However where I’m struggling is to pick up a selection change event inside a text box already selected. I need to be able to check if the textbox.SelStart is within an address value or within the string in the textbox.
The event Enter won’t work if the user is already editing the textbox (i.e. typing stuff) and then clicking or using the keyboard arrow to move the cursor somewhere else inside the textbox. I don’t think the event Change is the solution either as it would mean that the user would have already typed something and as a result the formula may already be broken.

I have had a good look around and I didn’t find an event for a selection change inside a textbox. Does it exists and/or is there a way that would have the same result?

Many thanks in advance.

@JosephP - would those work inside a form box? I wasn't sure and it seems the OP looked at some of the other events.

Thank you Josie and Pauley for your answers. This is very helpful I thought I hit a wall on that one but it seems that it could work.

The mouseup event works by using the code below from this website:

http://www.vbaexpress.com/forum/show...MouseUp-Events

Option Explicit 
Enum MouseButtons 
    fmButtonLeft = 1 'The left button was pressed.
    fmButtonRight = 2 'The right button was pressed.
    fmButtonMiddle = 4 'The middle button was pressed.
End Enum 
Private Sub TextBox1_MouseDown(ByVal Button As Integer, ByVal Shift As Integer, ByVal X As Single, ByVal Y As Single) 
    Select Case Button 
    Case fmButtonLeft 
        MsgBox "The left button was pressed" 
    Case fmButtonRight 
        MsgBox "The right button was pressed" 
    Case fmButtonMiddle 
        MsgBox "The middle button was pressed" 
    End Select 
End Sub

It seems that it is possible to use the KeyUp event but I can’t get that one to work yet. Here is the code I found:

Private Sub Textbox1_KeyUp(KeyCode As Integer, Shift As Integer)

    If KeyCode = vbKeyLeft Then
        MsgBox "Left arrow"
    ElseIf KeyCode = vbKeyRight Then
        MsgBox "Right arrow"
    End If
    
End Sub

I found it on this website.
http://vbcity.com/forums/t/12201.aspx

However I get the following error message:
Compile error:
Procedure declaration does not match description of event or procedure having the same name.

Is this to do with the declaration of KeyCode and Shift?

Thank you for your help

JL

Perfect! It works now with Rory’s procedure declaration

Thank you so much all!

J-L