add advanced option type that only shown when show advanced options is selected

frontend/apps/reader/modules/readermenu.lua

@@ -81,6 +81,14 @@ function ReaderMenu:setUpdateItemTable()
             G_reader_settings:saveSetting("night_mode", not night_mode)
         end
     })
+    table.insert(self.tab_item_table.main, {
+        text = _("Show advanced options"),
+        checked_func = function() return G_reader_settings:readSetting("show_advanced") end,
+        callback = function()
+            local show_advanced = G_reader_settings:readSetting("show_advanced") or false
+            G_reader_settings:saveSetting("show_advanced", not show_advanced)
+        end
+    })
     table.insert(self.tab_item_table.main, Language:getLangMenuTable())
     table.insert(self.tab_item_table.main, {
         text = _("Version"),

frontend/ui/widget/configdialog.lua

@@ -176,8 +176,10 @@ function ConfigOption:init()
     table.insert(vertical_group, VerticalSpan:new{
         width = Screen:scaleByDPI(default_option_padding),
     })
+    local show_advanced = G_reader_settings:readSetting("show_advanced") or false
     for c = 1, #self.options do
-        if self.options[c].show ~= false then
+        local show_default = not self.options[c].advanced or show_advanced
+        if self.options[c].show ~= false and show_default then
             local name_align = self.options[c].name_align_right and self.options[c].name_align_right or 0.33
             local item_align = self.options[c].item_align_center and self.options[c].item_align_center or 0.66
             local name_font_face = self.options[c].name_font_face and self.options[c].name_font_face or "cfont"