Reject "control" keys on keyDown event

I went with something like this:

function (e, inputElement) {
    // If the user gives the textbox any keyboard input, mark the input box as "dirty"
    var scope = this;
    var k = e.which;

    // Verify that the key entered is not a special key
    if (k == 20 /* Caps lock */
     || k == 16 /* Shift */
     || k == 9 /* Tab */
     || k == 27 /* Escape Key */
     || k == 17 /* Control Key */
     || k == 91 /* Windows Command Key */
     || k == 19 /* Pause Break */
     || k == 18 /* Alt Key */
     || k == 93 /* Right Click Point Key */
     || ( k >= 35 && k <= 40 ) /* Home, End, Arrow Keys */
     || k == 45 /* Insert Key */
     || ( k >= 33 && k <= 34 ) /*Page Down, Page Up */
     || (k >= 112 && k <= 123) /* F1 - F12 */
     || (k >= 144 && k <= 145 )) { /* Num Lock, Scroll Lock */
        return false;
    }
    else {
        scope.setPointValueDirtyStatus(inputElement, true);
    }
}

Use event.which -- Each key has its own code. Control key is 17, shift key is 16, and @ is two different keys, 16 followed by 50. Use the demo on that page to find out what values are returned for each key you want to accept or ignore.