How to disable the line under tool strip in winform c#?

Question

this line ?     

Answer 1

You might want to add type check to avoid missing border on ToolStripDropDownMenu/etc. (since inherited from ToolStrip, it starts same custom renderer usage automatically):

protected override void OnRenderToolStripBorder(ToolStripRenderEventArgs e)
{
    if (e.ToolStrip.GetType() == typeof(ToolStrip))
    { 
        // skip render border
    }
    else
    {
        // do render border
        base.OnRenderToolStripBorder(e);
    }
}

Missed ToolStripDropDownMenu border is not so noticable while using ToolStripSystemRenderer but become real eyesore with ToolStripProfessionalRenderer.

Also, setting System.Windows.Forms.ToolStripManager.Renderer = new MySR(); could be usefull if you want all ToolStrip instances appwide to use MySR by default.