Displaying few items in combo box :::: VB.Net

To control the number of items displayed in a comboBox you can use the MaxDropDownItems[^] property. But it won't behave the way you expect it to unless you also adjust the IntegralHeight[^] property. E.g.

ComboBox3.IntegralHeight = False
ComboBox3.MaxDropDownItems = 10

The second part of your requirement is a little strange but can be achieved by simply resetting IntegralHeight = True. You have to be careful where to place this - if you use the Click event for example the Dropdown will briefly show then close again (don't blink or you'll miss it!). This is probably the best idea

Private Sub ComboBox3_DropDownClosed(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles ComboBox3.DropDownClosed
    ComboBox3.IntegralHeight = True
End Sub