// [Copy List Data] Menu Item
private void copyListDataToolStripMenuItem_Click(object sender, EventArgs e)
{
if (formCopyListData == null)
{
formCopyListData = new CopyListData();
formCopyListData.MdiParent = this;
// In the current context += means subscribe. In other words it's like you are telling subscribe my method (the right operand)
// to this event (the left operand), this way, when the event is raised, your method will be called. Also, it is a good practice
// to unsubscribe (-= from this event, when you have finished your work ( but before you dispose you object ) in order to prevent
// your method being called and to prevent resource leaks.
formCopyListData.FormClosed += formCopyListData_FormClosed;
formCopyListData.Show();
}
else
{
// if the Form is already open
formCopyListData.Activate();
}
}
// [Copy List Data]
private void formCopyListData_FormClosed(object sender, FormClosedEventArgs e)
{
formCopyListData = null;
}