document.addEventListener('keydown', function (event) {
var tSpace = event.which == 32,
el = event.target,
input = el.nodeName != 'INPUT' && el.nodeName != 'TEXTAREA',
tStopPropagation = false;

if (input) {
if (tSpace) {
window.status = 'space';  // callback to RealStudio so we can stop the MsgBox
  tStopPropagation = true;
  }
  
  // this is to reset it to allow this command to work again
  // if we just clear out the 'space' status with an empty string, it does not work after the first time
  window.status = '-';
    
    if (tStopPropagation) {
    event.preventDefault();
      event.stopImmediatePropagation();
        }
        }
        }, true);

Sub StatusChanged(newStatus as String)
  if (newStatus = "space") then
    // you need to declare the variable first and then set its value, you cannot do this in a single line
    DIM tMoo As String
    tMoo = "cow"
  end if
End Sub