Event when a window gets maximized/un-maximized

Question

Is there an event that is fired when you maximize a Form or un-maximize it?

Before you say Resize or SizeChanged: Those get only fired if t

Answer 1

I'm a newbie here so comments not allowed, but this IS a comment to the clean answer by GeoTarget:

The first line OUGHT to be slightly changed to nullable, to catch if the form is started Minimized:

FormWindowState? LastWindowState = null;

And a banal suggestion: Move the assignment of LastWindowState to after the "if"s, so the user can easily check not only what you go to, but also what it came from:

FormWindowState? LastWindowState = null;
private void Form1_Resize(object sender, EventArgs e) {
    // When window state changes
    if (WindowState != LastWindowState) {
        if (WindowState == FormWindowState.Maximized) {
            // Maximized!
        }
        if (WindowState == FormWindowState.Normal) {
            // Restored!
        }
        LastWindowState = WindowState;
    }
}