Put status in button, and gray it out if morse is in progress.

Fix hint button.

morse/lib/morse/server.ex

@@ -17,6 +17,10 @@ defmodule Morse.Server do
     GenServer.call(__MODULE__, :progress)
   end
 
+  def in_progress? do
+    GenServer.call(__MODULE__, :in_progress?)
+  end
+
   @impl true
   def init(state) do
     {:ok, state}
@@ -24,11 +28,11 @@ defmodule Morse.Server do
 
   @impl true
   def handle_call(:start, _from, {pid, _progress} = state) do
-    if pid == nil or not Process.alive?(pid) do
+    if worker_alive?(pid) do
+      {:reply, {:error, :already_started}, state}
+    else
       pid = spawn(&Morse.Worker.signal/0)
       {:reply, :ok, {pid, 0}}
-    else
-      {:reply, {:error, :already_started}, state}
     end
   end
 
@@ -36,6 +40,10 @@ defmodule Morse.Server do
     {:reply, progress, state}
   end
 
+  def handle_call(:in_progress?, _from, {pid, _progress} = state) do
+    {:reply, worker_alive?(pid), state}
+  end
+
   @impl true
   def handle_cast({:progress, new_progress}, {pid, _progress}) do
     apply(pubsub(), :broadcast, [Ui.PubSub, "morse_progress", new_progress])
@@ -45,4 +53,8 @@ defmodule Morse.Server do
   defp pubsub do
     Application.fetch_env!(:morse, :pubsub)
   end
+
+  defp worker_alive?(pid) do
+    pid != nil and Process.alive?(pid)
+  end
 end