Question

How to make the child form follow main form.

for example: open a winform [.net2], winform opens form, form follows the mainform if mainform is moving.

Answer 1

Use the LocationChanged event from the MainForm to always set the location of the ChildForm.

Working example:

Form childForm = new Form();

protected override void OnLoad(EventArgs e) {
  base.OnLoad(e);

  childForm.StartPosition = FormStartPosition.Manual;
  childForm.Width = this.Width;
  childForm.Height = 96;
  childForm.Location = new Point(this.Left, this.Bottom);
  childForm.Show();
}

protected override void OnLocationChanged(EventArgs e) {
  base.OnLocationChanged(e);

  if (childForm != null) {
    childForm.Location = new Point(this.Left, this.Bottom);
  }
}