Hmmmm. If I understand you correctly you only want the user to be able to select a value from the listbox only once, is that correct? If this is correct you have a couple of options:
I might rewrite your original code something like:
Code:
Dim item as New ListItem
Dim dstval As String = ""
Dim distsel as Integer = 0
For Each item in lstDistrict.Items
If item.Selected Then
dstval += item.Value
lstDistrict.Items.Remove(item)
End If
Next
This will allow you to keep a distinct list of items the User has NOT selected. Alternatively you could put another listbox on your form and just move an item from your source list box to a temporary list box.
Code:
Dim item as New ListItem
Dim dstval As String = ""
Dim distsel as Integer = 0
For Each item in lstDistrict.Items
If item.Selected Then
dstval += item.Value
lstDistrictNew.Items.Add(item)
lstDistrict.Items.Remove(item)
End If
Next
and you would do the reverse if you wanted to move an item back to the source list box:
Code:
...
lstDistrict.Items.Add(item)
lstDistrictNew.Items.Remove(item)
I didn't test any of this but it should work for you without much problem.
hth.
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unselecting items in a listbox
