Form Border

Hello, Kashif,      

In Fluent theme the title bar is actually visible. It just has identical color as the form itself.

If you need to hide the title-bar itself, it is necessary to set the RadForm.FormElement.TitleBar.Visibility property to Collapsed.

        public RadForm1()
        {
            InitializeComponent();
            
            this.AllowTheming = true;
            this.FormElement.TitleBar.Visibility = ElementVisibility.Collapsed;
        }

Otherwise, set the RadForm.AllowTheming property to false and set the RadForm.BackColor to White:

        public RadForm1()
        {
            InitializeComponent();
            
            this.AllowTheming = false;
            this.BackColor = Color.White;  
        }

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