I suspect your code is jumping to where the TableAdapter is filled because by setting the DataSource of the ComboBox you're causing the SelectedIndexChanged
event to be fired.
So, you need to tell the SelectedIndexChanged
handler to return should the ToolStripComboBox not be populated yet, which you could do by setting a Boolean flag when the ToolStripComboBox has been populated. For example:
Dim m_ToolStripComboBoxPopulated As Boolean
Private Sub ToolStripComboBox_MessageType_Click(sender As Object, e As EventArgs) Handles ToolStripComboBox_MessageType.Click
Me.m_ToolStripComboBoxPopulated = False
Me.ToolStripComboBox_MessageType.ComboBox.DataSource = DataSet_UToolDb.XML_MESSAGE_TYPE
Me.ToolStripComboBox_MessageType.ComboBox.DisplayMember = "MessageType"
Me.ToolStripComboBox_MessageType.ComboBox.ValueMember = "MTId"
' Indicate ToolStripComboBox has been populated
Me.m_ToolStripComboBoxPopulated = True
End Sub
Private Sub ToolStripComboBox_MessageType_SelectedIndexChanged(sender As Object, e As EventArgs) Handles ToolStripComboBox_MessageType.SelectedIndexChanged
If (Me.m_ToolStripComboBoxPopulated = False) Then
Return
End If
Me.TableAdapter_XML_MESSAGE_STRUCTURE.Fill(DataSet_UToolDb.XML_MESSAGE_STRUCTURE, Me.ToolStripComboBox_MessageType.ComboBox.SelectedValue)
End Sub