Hello Hamidreza,
The issue is related to a change of the BindingContext in RadTreeView when its Parent ToolWindow changes its state from Dock to AutoHide. In this situation the Parent of the ToolWindow is changed and also the BindingContext is reset. I logged the issue in our Public Issue Tracking System. Currently, you can use BindingContextChanged event handler to work around the issue in your application:
using System;
using System.Data;
using System.Windows.Forms;
using Telerik.WinControls.UI;
namespace ForTest
{
public partial class Form1 : Form
{
private DataTable dtlevel = new DataTable();
private System.Drawing.Font NewFontObj = new System.Drawing.Font("Tahoma", 8F, System.Drawing.FontStyle.Regular);
public Form1()
{
InitializeComponent();
this.treelevel.BindingContextChanged += new EventHandler(treelevel_BindingContextChanged);
}
void treelevel_BindingContextChanged(object sender, EventArgs e)
{
LoadTreeView();
}
private void Form1_Load(object sender, EventArgs e)
{
dtlevel.Columns.Add ("LevelId",typeof(int));
dtlevel.Columns.Add("LevelName", typeof(string));
for (int i = 0; i < 4; i++)
{
DataRow dr = dtlevel.NewRow();
dr["LevelId"] = (i+1).ToString ();
dr["LevelName"] = " ??? " + (i + 1).ToString();
dtlevel.Rows.Add(dr);
}
LoadTreeView();
txtDetail.Font = NewFontObj;
btnOk.Font = NewFontObj;
txtDetail.Text = "ForTest";
}
private void LoadTreeView()
{
if (dtlevel.Columns.Count == 0)
{
return;
}
treelevel.DataSource = dtlevel;
treelevel.DisplayMember = dtlevel.Columns["LevelName"].Caption;
treelevel.ValueMember = dtlevel.Columns["LevelId"].Caption;
treelevel.CheckBoxes = true;
foreach (RadTreeNode node in treelevel.Nodes)
{
node.Checked = true;
node.Font = NewFontObj;
}
}
}
}
I hope this helps.
Regards,
Julian Benkov
the Telerik team