Determine what control the ContextMenuStrip was used on

For a ContextMenu:

The problem is that the sender parameter points to the item on the context menu that was clicked, not the context menu itself.

It's a simple fix, though, because each MenuItem exposes a GetContextMenu method that will tell you which ContextMenu contains that menu item.

Change your code to the following:

private void MenuViewDetails_Click(object sender, EventArgs e)
{
    // Try to cast the sender to a MenuItem
    MenuItem menuItem = sender as MenuItem;
    if (menuItem != null)
    {
        // Retrieve the ContextMenu that contains this MenuItem
        ContextMenu menu = menuItem.GetContextMenu();

        // Get the control that is displaying this context menu
        Control sourceControl = menu.SourceControl;
    }
}

For a ContextMenuStrip:

It does change things slightly if you use a ContextMenuStrip instead of a ContextMenu. The two controls are not related to one another, and an instance of one cannot be casted to an instance of the other.

As before, the item that was clicked is still returned in the sender parameter, so you will have to determine the ContextMenuStrip that owns this individual menu item. You do that with the Owner property. Finally, you'll use the SourceControl property to determine which control is displaying the context menu.

Modify your code like so:

private void MenuViewDetails_Click(object sender, EventArgs e)
{
     // Try to cast the sender to a ToolStripItem
     ToolStripItem menuItem = sender as ToolStripItem;
     if (menuItem != null)
     {
        // Retrieve the ContextMenuStrip that owns this ToolStripItem
        ContextMenuStrip owner = menuItem.Owner as ContextMenuStrip;
        if (owner != null)
        {
           // Get the control that is displaying this context menu
           Control sourceControl = owner.SourceControl;
        }
     }
 }

Older post, but in case someone like myself comes across it:

For a ContextMenuStrip, the above didn't work for me, but it led to finding what did.

void DeleteMenu_ItemClicked(object sender, ToolStripItemClickedEventArgs e)
{
    ContextMenuStrip menu = sender as ContextMenuStrip;
    Control sourceControl = menu.SourceControl;
    MessageBox.Show(sourceControl.Name);
}

This gave me the expected control's name. You can put in validation etc with if statements, I'm just posting to get to the point.