C # display the child form in the parent container

Form2 form = new form2 ();
Form. formborderstyle = formborderstyle. None;
// Hide the border of the child form (remove the smallest flower, maximize, close, and other buttons)
Form. toplevel = false;
// Indicates that the subform is not a top-level form.
This. panel1.controls. Add (form); // load the subform into the panel.
Form. Show ();

Method 2: Specify the parent container implementation
Form2
Form = new
Form2 ();
Form. mdiparent = This; // specify the current form as the top-level MDI form
Form. Parent = This. Panel1; // indicates that the parent container of the child form is
FRM. formborderstyle
= Formborderstyle. None; // hide the border of the sub-form. Of course, it can also be implemented in the form loading event of the sub-form.
Panelform. Show ();