I think this is possibly the solution. Since the function 'OnEditchangeCombo1' is defined in the dialog window's class, you should just do this:
When 'OR'ing something in functions such as 'Create()' you should only use one '|' symbol. Also, I think you have to pass a reference to the rectangle, since the function asks for a pointer to a 'RECT' object, and 'CRect' objects are basically 'RECT' objects. Or you could just do this:
getFile.Create(CBS_DROPDOWNLIST | WS_VISIBLE , &pos, this, 1);
And change the '&pos' to just 'pos'. I believe this is the answer. If not, at least I put in some effort and ATTEMPTED to help.
CRect *pos = new CRect(0, 0, 20, 20); // New 'CRect' pointer