>If you have a combobox, which is dropdown list, after you make your selection, how can you return to default (empty state)?
>Suppose, you have a field in your main table, which may contain a coded value or could be empty. For this field you use a combobox (drop down list). Suppose, you choose something. How then could you return it back to empty state? Seems there is no way, unless you would code some event to do so, say, Right Click.

You'd have to include an empty member of the row source.
e.g.,

WITH thisform
  DIMENSION .aRow(3)
  .aRow[1] = ""
  .aRow[2] = "hello"
  .aRow[3] = "world"
  .cboCombo.RowSourceType = 5
  .cboCombo.RowSource = "thisform.aRow"
  .cboCombo.Requery()

** or
  .cboCombo.RowSourceType = 1
  .cboCombo.RowSource = ",hello,world"
  .cboCombo.Requery()

ENDWITH