Making button invisible if nothing from Combobox is selected

[Michael Mitchell]

Can someone help me generate a code so that when nothing from a Combobox (Who's drop down style is: DropDownList) is selected then a certain button becomes invisible until something is selected.

Code: If cboEnvironment.Text.Length = 0 Then
btnSubmit.Visible = False
End If

[Edgemeal]

When nothing is selected the selected index will equal -1

try,

Private Sub cboEnvironment_SelectedIndexChanged(sender As System.Object, e As System.EventArgs) Handles cboEnvironment.SelectedIndexChanged
    If cboEnvironment.SelectedIndex = -1 Then
        btnSubmit.Visible = False
    Else
        btnSubmit.Visible = True
    End If
End Sub

[IanRyder]

Hi,

Edgemeal is correct but:-

Other than on Form Load where this ComboBox may not have anything selected, using the DropDownStyle, DropDownList, does NOT allow you to deselect an option that has already been selected so your question is a mute point at this time??

I guess there is something more to this question?

Cheers,

Ian

[Edgemeal]

Not sure I understand what you mean, to unselect just set the index to -1.

Public Class Form1

    Private Sub Form1_Load(sender As System.Object, e As System.EventArgs) Handles MyBase.Load
        ' on startup hide btnSubmit
        btnSubmit.Visible = False
    End Sub

    Private Sub cboEnvironment_SelectedIndexChanged(sender As System.Object, e As System.EventArgs) Handles cboEnvironment.SelectedIndexChanged
        ' when combo index changes check selected index value
        If cboEnvironment.SelectedIndex = -1 Then ' no item selected
            btnSubmit.Visible = False
        Else ' item is selected
            btnSubmit.Visible = True
        End If
    End Sub

    Private Sub Button1_Click(sender As System.Object, e As System.EventArgs) Handles Button1.Click
        ' reset combo selection
        cboEnvironment.SelectedIndex = -1
    End Sub

    Private Sub btnSubmit_Click(sender As System.Object, e As System.EventArgs) Handles btnSubmit.Click
        ' submit was click, do something..
    End Sub
End Class

[IanRyder]

Sorry Edgemeal,

Yes, you can set this back to -1 in Code, but I was thinking more along the lines of a user not being able to set this back to an Unselected option using the drop down style being used.

Apologies for the confusion and maybe this is the additional question I was expecting?

Cheers,

Ian