ScreenSaver: Allow toggling the reboot/poweroff overlay message (#7566)

Co-authored-by: gbyl <gbyl@users.noreply.github.com>

frontend/ui/elements/screensaver_menu.lua

@@ -194,6 +194,15 @@ return {
                             G_reader_settings:saveSetting("screensaver_msg_background", "none")
                         end,
                     },
+                    {
+                        text = _("Hide reboot/poweroff message"),
+                        checked_func = function()
+                            return G_reader_settings:isTrue("screensaver_hide_fallback_msg")
+                        end,
+                        callback = function()
+                            G_reader_settings:toggle("screensaver_hide_fallback_msg")
+                        end,
+                    },
                     {
                         text = _("Message position"),
                         sub_item_table = {

frontend/ui/screensaver.lua

@@ -46,6 +46,9 @@ end
 if G_reader_settings:hasNot("screensaver_delay") then
     G_reader_settings:saveSetting("screensaver_delay", "disable")
 end
+if G_reader_settings:hasNot("screensaver_hide_fallback_msg") then
+    G_reader_settings:makeFalse("screensaver_hide_fallback_msg")
+end
 
 local Screensaver = {
     screensaver_provider = {
@@ -385,7 +388,7 @@ function Screensaver:setup(event, fallback_message)
     if G_reader_settings:has(self.prefix .. "screensaver_type") then
         self.screensaver_type = G_reader_settings:readSetting(self.prefix .. "screensaver_type")
     else
-        if event then
+        if event and G_reader_settings:isFalse("screensaver_hide_fallback_msg") then
             -- Display the provided fallback_message over the screensaver,
             -- so the user can distinguish between suspend (no overlay),
             -- and reboot/poweroff (overlaid message).