how about using a $input for the errors instead of 2 other dialogs?

maybe something like

noop $input(Please enter a Message in the provided edit box.,uhdo,Message Error)
noop $input(Please enter an Action in the provided edit box.,uhdo,Action Error)

so it would look something like this

on *:dialog:gsm:sclick:*:{ 
  if ($did == 3) {
    if (!$did(2).text) { noop $input(Please enter a Message in the provided edit box.,uhdo,Message Error) }
    else { scid -a amsg $did(2).text }
  }
  if ($did == 6) {
    if (!$did(5).text) { noop $input(Please enter an Action in the provided edit box.,uhdo,Action Error) }
    else { scid -a ame $did(5).text }
  }
}

as well to open ur dialog maybe use

 dialog $iif($dialog(gsm),-v,-m gsm) gsm

so you dont get an error if you try to open it again for some reason