Here is a proper way to do it - inherit a class from native ComboBox and override OnDropDown to raise a custom DropDownOpening event first: Public Class MyComboBox : Inherits ComboBox Public Event DropDownOpening(sender As Object, e As System.EventArgs) Protected Overrides Sub OnDropDown(e As System.EventArgs) RaiseEvent DropDownOpening(Me, e) MyBase.OnDropDown(e) End SubEnd ClassPrivate Sub MyComboBox1_DropDownOpening(sender As Object, e As System.EventArgs) Handles MyComboBox1.DropDownOpening 'reload your list here '... End SubIf you anticipate loading to take considerable time, you can wrap your reload code into a construct like this: Dim oldCursor As Cursor = MyComboBox1.CursorMyComboBox1.Cursor = Cursors.WaitCursor'reload your list here'...MyComboBox1.Cursor = oldCursor(DoEvents is not needed to propagate cursor change)
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