Don't bother setting the contextMenuStrip property on the TabControl. Rather do it this way. Hook up to the tabControl's MouseClick event, and then manually show the context menu. This will only fire if the tab itself on top is clicked on, not the actual page. If you click on the page, then the tabControl doesn't receive the click event, the TabPage does. Some code:
public Form1()
{
InitializeComponent();
this.tabControl1.MouseClick += new MouseEventHandler(tabControl1_MouseClick);
}
private void tabControl1_MouseClick(object sender, MouseEventArgs e)
{
if (e.Button == MouseButtons.Right)
{
this.contextMenuStrip1.Show(this.tabControl1, e.Location);
}
}