'Accessing Textbox Methods through Object Variable

Q. This is what I`m trying to do:

Dim a As TextBox
Set a = Text1

Private Sub Text1_MouseDown(Button As Integer, Shift As Integer, X As 
Single, Y As Single)

This is the mouse down method for a text box. I want to use this method through 
the variable a. I`ve been told I`d need to use inheritance, and
polymorphism. 

A. You do not need inheritance and polymorphism here. As long as the variable 
has visible scope within the module with the Text1_MouseDown event, you can use 
that variable to call the TextBox it references. Modify your code like this:

'In the Form's declaration section
Private a As TextBox

'In the Form_Load event
Set a = Text1

Then, anywhere within that form, including Text1_MouseDown, you can do this...

a.Text = "Put new text here"

anytime you want to change Text1`s content. Incidentally, if you declare a as 
public:

Public a As TextBox

Then you can also refer to a outside of the form using Form1.a assuming the form 
containing Text1 is Form1.

Thanks to: Taiwo Ayedun