How to disable the parent form when a child form is active?

Question

How to disable a parent form when child form is active using c#?

Answer 1

You can also use MDIParent-child form. Set the child form's parent as MDI Parent

Eg

child.MdiParent = parentForm;
child.Show();

In this case just 1 form will be shown and the child forms will come inside the parent. Hope this helps