How to reproduce:
partial class Form2
{
/// <summary>
/// Required designer variable.
/// </summary>
private System.ComponentModel.IContainer components = null;
/// <summary>
/// Clean up any resources being used.
/// </summary>
/// <param name="disposing">true if managed resources should be disposed; otherwise, false.</param>
protected override void Dispose(bool disposing)
{
if (disposing && (components != null))
{
components.Dispose();
}
base.Dispose(disposing);
}
#region Windows Form Designer generated code
/// <summary>
/// Required method for Designer support - do not modify
/// the contents of this method with the code editor.
/// </summary>
private void InitializeComponent()
{
this.radTrackBar1 = new Telerik.WinControls.UI.RadTrackBar();
((System.ComponentModel.ISupportInitialize)(this.radTrackBar1)).BeginInit();
this.SuspendLayout();
//
// radTrackBar1
//
this.radTrackBar1.Anchor = ((System.Windows.Forms.AnchorStyles)((System.Windows.Forms.AnchorStyles.Top | System.Windows.Forms.AnchorStyles.Right)));
this.radTrackBar1.BackColor = System.Drawing.Color.FromArgb(((int)(((byte)(233)))), ((int)(((byte)(240)))), ((int)(((byte)(249)))));
this.radTrackBar1.Font = new System.Drawing.Font("Segoe UI", 8.25F, System.Drawing.FontStyle.Regular, System.Drawing.GraphicsUnit.Point, ((byte)(0)));
this.radTrackBar1.LabelStyle = Telerik.WinControls.UI.TrackBarLabelStyle.BottomRight;
this.radTrackBar1.LargeChange = 5;
this.radTrackBar1.LargeTickFrequency = 139;
this.radTrackBar1.Location = new System.Drawing.Point(36, 69);
this.radTrackBar1.Maximum = 140F;
this.radTrackBar1.Minimum = 1F;
this.radTrackBar1.Name = "rTrackBar1";
this.radTrackBar1.Size = new System.Drawing.Size(243, 33);
this.radTrackBar1.SmallTickFrequency = 5;
this.radTrackBar1.SnapMode = Telerik.WinControls.UI.TrackBarSnapModes.None;
this.radTrackBar1.TabIndex = 0;
this.radTrackBar1.Text = "rTrackBar1";
this.radTrackBar1.ThemeName = "ControlDefault";
this.radTrackBar1.TickStyle = Telerik.WinControls.Enumerations.TickStyles.None;
this.radTrackBar1.Value = 80F;
((Telerik.WinControls.UI.RadTrackBarElement)(this.radTrackBar1.GetChildAt(0))).MinSize = new System.Drawing.Size(100, 0);
((Telerik.WinControls.UI.TrackBarBodyElement)(this.radTrackBar1.GetChildAt(0).GetChildAt(1))).Margin = new System.Windows.Forms.Padding(7, 0, 7, 0);
((Telerik.WinControls.UI.TrackBarScaleContainerElement)(this.radTrackBar1.GetChildAt(0).GetChildAt(1).GetChildAt(0))).Orientation = System.Windows.Forms.Orientation.Vertical;
((Telerik.WinControls.UI.TrackBarScaleElement)(this.radTrackBar1.GetChildAt(0).GetChildAt(1).GetChildAt(0).GetChildAt(2))).Orientation = System.Windows.Forms.Orientation.Vertical;
((Telerik.WinControls.UI.TrackBarScaleElement)(this.radTrackBar1.GetChildAt(0).GetChildAt(1).GetChildAt(0).GetChildAt(2))).StretchVertically = false;
((Telerik.WinControls.UI.TrackBarLabelContainerElement)(this.radTrackBar1.GetChildAt(0).GetChildAt(1).GetChildAt(0).GetChildAt(2).GetChildAt(1))).StretchVertically = false;
((Telerik.WinControls.UI.TrackBarLabelElement)(this.radTrackBar1.GetChildAt(0).GetChildAt(1).GetChildAt(0).GetChildAt(2).GetChildAt(1).GetChildAt(0))).Text = "Lo";
((Telerik.WinControls.UI.TrackBarLabelElement)(this.radTrackBar1.GetChildAt(0).GetChildAt(1).GetChildAt(0).GetChildAt(2).GetChildAt(1).GetChildAt(1))).Text = "Hi";
//
// Form2
//
this.AutoScaleDimensions = new System.Drawing.SizeF(6F, 13F);
this.AutoScaleMode = System.Windows.Forms.AutoScaleMode.Font;
this.ClientSize = new System.Drawing.Size(822, 515);
this.Controls.Add(this.radTrackBar1);
this.Name = "Form2";
this.Text = "Form2";
((System.ComponentModel.ISupportInitialize)(this.radTrackBar1)).EndInit();
this.ResumeLayout(false);
this.PerformLayout();
}
#endregion
private Telerik.WinControls.UI.RadTrackBar radTrackBar1;
}
Workaround: remove setting of the text from the designer file to the Shown event of the form
public partial class Form2 : Form
{
public Form2()
{
InitializeComponent();
}
protected override void OnShown(EventArgs e)
{
base.OnShown(e);
((Telerik.WinControls.UI.TrackBarLabelElement)(this.radTrackBar1.GetChildAt(0).GetChildAt(1).GetChildAt(0).GetChildAt(2).GetChildAt(1).GetChildAt(0))).Text = "Lo";
((Telerik.WinControls.UI.TrackBarLabelElement)(this.radTrackBar1.GetChildAt(0).GetChildAt(1).GetChildAt(0).GetChildAt(2).GetChildAt(1).GetChildAt(1))).Text = "Hi";
}
}