Disable borders TabbedForm

Hello, Serg, 

You can specify the FormElement.BorderThickness property. However, it is necessary to set it at least to 1 in order to be able to resize the form. An alternative approach is to completely collapse the border element.

        private void RadTabbedForm1_Shown(object sender, EventArgs e)
        {
            this.FormBorderStyle = FormBorderStyle.SizableToolWindow;
            this.ControlBox = false; 
            this.FormElement.Border.Visibility = ElementVisibility.Collapsed;
        }

I hope this information helps. If you need any further assistance please don't hesitate to contact me. 

Regards,
Dess | Tech Support Engineer, Sr.
Progress Telerik

Hello, Serg,

By default, the AllowAero property of the RadTabbedForm is disabled. If you enable it, you will obtain slightly different look of the form's border as it is illustrated below:

AllowAero= false:

AllowAero= true:

Thus, you can obtain maximum space of the client area in the form. Please give it a try and see how it would work for your scenario.

Should you have further questions please let me know.

Regards,
Dess | Tech Support Engineer, Sr.
Progress Telerik