Keyboard Navigation in Windows Forms Popup (PopupControlContainer)
When the popup is visible, the PopupControlContainer will look for Alt, Enter, Tab, Esc, F4, and F2 keys to close the popup. If user want to change this, set IgnoreDialogKey property to
true and should make sure to close the popup manually by using HidePopup method.
By default, the IgnoreDialogKey property is set as
this.popupControlContainer1.IgnoreDialogKey = true;
Me.popupControlContainer1.IgnoreDialogKey = True