#pas
with Control{$ifndef F_P}^{$endif} do
begin
  if (_prop_ReadOnly <> 0) then OnChange := _OnChange;
  Text := _prop_Text; //кто тут говорил, что не инициализируется?
  OnSelChange := _OnClick;
  if ManFlags and $8 > 0 then OnDrawItem  := _OnDrawItem;
  if (Count > 0) and (_prop_ReadOnly = 0) then CurIndex := 0;  //а вот и виновник события из первого поста
end;

#pas
procedure THIComboBox.Init;
var  Flags:TComboOptions;
     dt:TData; //***
begin
  Flags := [{coNoIntegralHeight}];
  dtString(dt, _prop_Text); //***
  if (_prop_ReadOnly = 0) then include(Flags,coReadOnly);
  if _prop_Sort then include(Flags,coSort);
  if ManFlags and $8 > 0 then include(Flags,coOwnerDrawFixed);
  Control := NewCombobox(FParent,Flags);
  Control.OnMeasureItem:= _OnMeasureItem;    
  inherited;
  SetStrings(_prop_Strings);
  with Control{$ifndef F_P}^{$endif} do
  begin
    if (_prop_ReadOnly <> 0) then OnChange := _OnChange;
    Text := _prop_Text;
    OnSelChange := _OnClick;
    if ManFlags and $8 > 0 then OnDrawItem  := _OnDrawItem;
    //if (Count > 0) and (_prop_ReadOnly = 0) then CurIndex := 0;
    if (Count > 0) and (_prop_ReadOnly = 0) then _work_doSelectString(dt,0);//***
  end;
end;