Confused ComboBox

[MrGTI]

This is one weird glitch. I've searched the forums and the web, and still i have not found anyone else that has encountered this.

On a WinForm, drop on 2 ComboBoxes, and then place this code in behind it:

Dim bFormLoading As Boolean = True
 
    Private Sub Form1_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
        Dim arText() As String = {"", "Red", "White", "Blue"}
        ComboBox1.DataSource = arText
        ComboBox2.DataSource = arText
        'MsgBox("form_load")
        bFormLoading = False
    End Sub
 
    Private Sub ComboBox1_SelectedIndexChanged(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles ComboBox1.SelectedIndexChanged
        If bFormLoading = False Then MsgBox("ComboBox1")
    End Sub
 
    Private Sub ComboBox2_SelectedIndexChanged(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles ComboBox2.SelectedIndexChanged
        If bFormLoading = False Then MsgBox("ComboBox2")
    End Sub

When you run the program and select something from either combo box, the code for both fires!

I think it's some kind of weird situation where .NET is re-drawing the form, and thus it is re-selecting an item in each combo box. But i'm not sure.

It's the weirdest thing i've ever seen.

[Lunatic3]

It is not related to form painting event. As obvious in your code, you have bound tow comboboxes to one datasource and when you change one combobox the underlying binding manager position changes, so it fires the other combobox.

[MrGTI]

I accept your answer, but logically it doesn't make sense. At least from a programming aspect.

In this case you want to have the user select two different colours. So you populate the combo boxes with the colours available in the array.

Having to create a second array with the same values defeats the purpose of having the array, since you lose the single place to update all available elements.

Personally i think this is a bug in the .NET code.

I created another array and it works, so thanks a lot for your help!

[Lunatic3]

Well, am not that experienced to judge if it is a bug or not, but IMHO its not, its just the nature of binding i guess. Why dont you just populate your comboboxes with the array instead of binding to that array?

[MrGTI]

You say i should populate instead of binding.... Can you give me an example of what you are thinking?

[Lunatic3]

Too easy

Dim arText() As String = {"", "Red", "White", "Blue"}
        ComboBox1.Items.AddRange(arText)
        ComboBox2.Items.AddRange(arText)

[MrGTI]

Well what do you know..... It worked!

I had no idea you could do that. All the examples i'd seen used the DataSource property.

I have learned some very important today. Thanks Lunatic3!

[Lunatic3]

You're most welcome!