Dan,

I just created a form with this code:

*Load()
dimension this.maList[50]

for i = 1 to 50
   this.maList[i] = "test" + str(i) && yellow
endfor

*Click()
for i = 1 to 50 step 2
   this.list1.Selected[i] = .t.
endfor

* these properties
RowSourceType = 5
RowSource = "thisform.maList"
Height = 170
Left = 17
MultiSelect = .T.
Top = 38
Width = 100
Name = "List1"

When I click the form the items multiselect. I can then continue to Ctrl-Click other items to select them as well.

>This did not help. Actually, I have a combo box on the form. In the InterAcitveChange event of the combo box, I select items in the list box. When going to the list box to override the selections, by CTRL-Clicking on other items, the items selected by code are de-selected.