set focus from treeview to control

4 May 2006 3:18 PM

mongphong28

Hi,

I'm using a treeview as a menu, and when the user clicks on a node I
want the focus to set to a control (ie textbox) in a panel to the
right. The problem I'm having is the focus will not stay on the
control, but instead jumps back to the treeview.

I'm setting the focus in the AfterSelect event of the treeview, and if
I step through the code the desired control does have .Focused = True
after I have set it, but then somewhere after the AfterSelect event the
focus changes back to the listview. I have no other code after the
focus is set to the control.

Is there a better event I should be doing this in, or something else I
need to do to stop the focus jumping back to the treeview.

Regards,
Mong

5 May 2006 3:42 PM

jayeldee

Mong,

I was having a similar problem in an app and my workaround may or may
not work for you. If you put the thread to sleep for a second during
the TextBox.GotFocus event you'll see that the TreeView hasn't fully
updated when the AfterSelect is fired. The node you click is still
highlighted in gray instead of the dark blue. I'm assuming this is
part of the reason it steals the focus back - to redraw itself.

My method.

I have a generic handler, FocusHandler( ) that handles the GotFocus
event for all the controls that get focus from the TreeView.   I set a
form-level boolean (GiveMeBackMyFocus) to true in this Handler.
In the TreeView.GotFocus event, I check this boolean. If it's set to
True, then the TreeView gives control back and sets it to False to
prevent it from firing again.

I track the control that needs focus with a form-level
System.Windows.Forms.Control variable that is set during the
AfterSelect event.

Here's a quick example of how I implemented it:

Public Class Form1
    Inherits System.Windows.Forms.Form

#Region " Windows Form Designer generated code "
#End Region

    Private textBoxNode As TreeNode
    Private listNode As TreeNode
    Private otherNode As TreeNode
    Private GiveMeBackMyFocus As Boolean
    Private controlToFocus As Control

    Private Sub Form1_Load(ByVal sender As System.Object, ByVal e As
System.EventArgs) Handles MyBase.Load

        textBoxNode = Me.TreeView1.Nodes.Add("TextBox Node")
        listNode = Me.TreeView1.Nodes.Add("Listbox Node")
        otherNode = Me.TreeView1.Nodes.Add("Other Node")

    End Sub

    Private Sub TreeView1_AfterSelect(ByVal sender As System.Object,
ByVal e As System.Windows.Forms.TreeViewEventArgs) Handles
TreeView1.AfterSelect

        If e.Node Is textBoxNode Then
            Me.controlToFocus = Me.TextBox1
        ElseIf e.Node Is Me.listNode Then
            Me.controlToFocus = Me.ListBox1
        Else
            Return
        End If

        Me.ActiveControl = Me.controlToFocus

    End Sub

    Private Sub FocusHandler(ByVal sender As System.Object, ByVal e As
System.EventArgs) Handles TextBox1.GotFocus, ListBox1.GotFocus
        Me.GiveMeBackMyFocus = True
    End Sub

    Private Sub TreeView1_GotFocus(ByVal sender As Object, ByVal e As
System.EventArgs) Handles TreeView1.GotFocus
        If Me.GiveMeBackMyFocus Then
            Me.controlToFocus.Focus()
            Me.GiveMeBackMyFocus = False
        End If
    End Sub

End Class

John