How to remove this strange visual artifact in the corner of ToolStrip Winforms control?

Question

Here is the picture that shows the problem. Take a look at the bottom right corner.

Anyone knows how to get rid of it?

Setting LayoutStyle to

Answer 1

Sorry for being late to the party, but the accepted answer didn't work for my needs. The following solution is what I came up with:

Getting rid of the black line

1) Create a custom renderer:

class CustomToolStripProfessionalRenderer : ToolStripProfessionalRenderer
{
    protected override void OnRenderToolStripBorder(ToolStripRenderEventArgs e)
    {
        // Don't draw a border
    }
}

2) Use the custom renderer:

toolStrip1.Renderer = new CustomToolStripProfessionalRenderer();

Getting rid of the background

The above solution satisfies the need of the original question, but I didn't like the gradient background on the ToolStrip either. I wanted the ToolStrip to be an "invisible" container:

1) Create a custom color table:

class CustomProfessionalColorTable : ProfessionalColorTable
{
    public override Color ToolStripGradientBegin
    {
        get { return SystemColors.Control; }
    }

    public override Color ToolStripGradientMiddle
    {
        get { return SystemColors.Control; }
    }

    public override Color ToolStripGradientEnd
    {
        get { return SystemColors.Control; }
    }
}

2) Use the custom color table:

class CustomToolStripProfessionalRenderer : ToolStripProfessionalRenderer
{
    public CustomToolStripProfessionalRenderer()
        : base(new CustomProfessionalColorTable())
    {

    }

    protected override void OnRenderToolStripBorder(ToolStripRenderEventArgs e)
    {
        // Don't draw a border
    }
}