Hello Frank,

As it is very hard for me to distinct this border, could you please try the following code and tell me if you see any difference with and without it:

   ultraButton_OK1.HotTrackAppearance.BorderColor = Color.Gray;

I will be waiting for your feedback. 

Hi Boris

Thanks a lot for your answer.

Well, I have the form BackColor and the Button BackColor the same.
When I show the form it looks fine, no little black border arround the button.
But when I move the mouse over the button I get a thin black border
arround the button, as you see in my screenshot. I dont know where it comes from ??

Regards
Frank Uray

Hi Boris

Here are my settings:

            this.ultraButton_OK.Anchor = ((System.Windows.Forms.AnchorStyles)((System.Windows.Forms.AnchorStyles.Bottom | System.Windows.Forms.AnchorStyles.Right)));
            appearance1.ForeColor = System.Drawing.Color.White;
            this.ultraButton_OK.Appearance = appearance1;
            this.ultraButton_OK.ButtonStyle = Infragistics.Win.UIElementButtonStyle.FlatBorderless;
            appearance2.BackColor = System.Drawing.Color.Gray;
            appearance2.FontData.UnderlineAsString = "True";
            appearance2.ForeColor = System.Drawing.Color.LightGreen;
            this.ultraButton_OK.HotTrackAppearance = appearance2;
            this.ultraButton_OK.Location = new System.Drawing.Point(210, 11);
            this.ultraButton_OK.Name = "ultraButton_OK";
            appearance3.BackColor = System.Drawing.Color.Gray;
            this.ultraButton_OK.PressedAppearance = appearance3;
            this.ultraButton_OK.Size = new System.Drawing.Size(75, 23);
            this.ultraButton_OK.TabIndex = 1;
            this.ultraButton_OK.Text = "OK";
            this.ultraButton_OK.UseOsThemes = Infragistics.Win.DefaultableBoolean.False;
            this.ultraButton_OK.Click += new System.EventHandler(this.ultraButton_OK_Click);