Using UI for WinForms R3 2017 (version 2017.3.912) Strange behavior while selecting text with the mouse, while TextAlign is set to Right and there is more text then visible. To reproduce try selecting all the text in the control from the attached file (once to the left, once to the right). If the ShowClear button is visible and RihtToLeft is true, it won't select to the left (while there is more text than visible). RadTextBoxControl radTextBoxControl1 = new Telerik.WinControls.UI.RadTextBoxControl(); this.radTextBoxControl1.Location = new System.Drawing.Point(239, 186); this.radTextBoxControl1.Name = "radTextBoxControl1"; this.radTextBoxControl1.RightToLeft = System.Windows.Forms.RightToLeft.Yes; this.radTextBoxControl1.ShowClearButton = true; this.radTextBoxControl1.Size = new System.Drawing.Size(64, 20); this.radTextBoxControl1.TabIndex = 6; this.radTextBoxControl1.Text = "123456789123456789"; this.radTextBoxControl1.TextAlign = System.Windows.Forms.HorizontalAlignment.Right;