I have a really strange problem.
I have a textbox "myTextbox" and a listbox "myList" which shows a list of strings e.g "AAA", "BBB", "CCCC".

When the user clicks on an item from the listbox the text must be appended to the end of whatever is in myTextbox with a space preceeding it. e.g " AAA".

The user must never be allowed to delete the added text.

The user must be allowed to manually enter text in the textbox but it must always be in front of the added text.

They must never be allowed to type over the added text or after the added text.


I have been trying to get my head around this for a day now and cannot figure it out.
Can anyone point me in the right direction?
Has anyone had a similar request to deal with?

Thanks in advance