Question

I’m building a Windows Forms application in C#. How do I trigger code when a certain tab on a tab menu is selected?

Answer 1

I think it is the TabControl.SelectedIndexChanged event.

Just look at MSDN. I took it from there. Suppose you named your tab control tabControl1.
You need to subscribe to this event using:

tabContrl1.TabControl.SelectedIndexChanged += tabControl1_SelectedIndexChanged;

And add the event handler

private void tabControl1_SelectedIndexChanged(Object sender, EventArgs e) {

   MessageBox.Show("You are in the TabControl.SelectedIndexChanged event.");
}