ui: augment pairing message for devices with multiple channels

lib/solaar/cli/pair.py

@@ -109,7 +109,9 @@ def run(receivers, args, find_receiver, _ignore):
 
     else:
         receiver.set_lock(False, timeout=timeout)
-        print("Pairing: turn your new device on (timing out in", timeout, "seconds).")
+        print("Pairing: Turn your device on or press, hold, and release")
+        print("a channel button or the channel switch button.")
+        print("Timing out in", timeout, "seconds.")
         pairing_start = time()
         patience = 5  # the lock-open notification may come slightly later, wait for it a bit
         while receiver.pairing.lock_open or time() - pairing_start < patience:

lib/solaar/ui/pair_window.py

@@ -45,10 +45,20 @@ def create(receiver):
         else:
             text = _("Other receivers are only compatible with a few devices.")
         text += "\n\n"
-        text += _("Turn on the device you want to pair.")
+        text += _("For most devices, turn on the device you want to pair.")
+        text += _("If the device is already turned on, turn it off and on again.")
+        text += "\n"
         text += _("The device must not be paired with a nearby powered-on receiver.")
         text += "\n"
-        text += _("If the device is already turned on, turn it off and on again.")
+        text += _(
+            "For devices with multiple channels, "
+            "press, hold, and release the button for the channel you wish to pair"
+            "\n"
+            "or use the channel switch button to select a channel "
+            "and then press, hold, and release the channel switch button."
+        )
+        text += "\n"
+        text += _("The channel indicator light should be blinking rapidly.")
     if receiver.remaining_pairings() and receiver.remaining_pairings() >= 0:
         text += (
             ngettext(