How to determine which control on form has focus?

Question

I\'ve read elsewhere on here that to capture \"Enter\" key stroke in a text box and use it as if pushing a button I should set the KeyPreview property of the form to true an

Answer 1

I've found a solution which appears to be working.

    private void DeviceForm_KeyDown(object sender, KeyEventArgs e)
    {
        if (e.KeyValue == 13 && tstxtDeviceFilter.Focused)
        {
            filterByDeviceSN();
        }
    }

I can't help but think there must be a better way though!

--EDIT--EDIT--EDIT--EDIT--EDIT--

Well, after looking at the suggestions below (thank you) I've found a 'better' way for me in this circumstance.

    this.tstxtDeviceFilter.KeyDown += new System.Windows.Forms.KeyEventHandler(this.tstxtDeviceFilter_KeyDown);

    private void tstxtDeviceFilter_KeyDown(object sender, KeyEventArgs e)
    {
        if (e.KeyValue == 13)
        {
            filterByDeviceSN();
        }
    }

Obviously by trapping the event on the textbox itself rather than the form I don't need to worry about focus. Once again I feel dumb for not thinking of that for so long!