Let's have a TextBox, ToolTip and a FloatingWindow containing the TextBox. The following code snippet will not show a tooltip for the textbox:
            this.toolTip1.ToolTipTitle = "ToolTip";  
            string strToolTip = "Exemple";  
            this.toolTip1.SetToolTip(textBox1, strToolTip);  
            this.toolTip1.AutoPopDelay = 32767; 
            this.toolTip1.Active = true;