TouchMenu: open to items page when going up a level

Builds on #7490

frontend/dispatcher.lua

@@ -542,6 +542,7 @@ function Dispatcher:addItem(caller, menu, location, settings, section)
                         end
                     end,
                     separator = settingsList[k].separator,
+                    menu_item_id = k,
                 })
             end
         end

frontend/ui/widget/touchmenu.lua

@@ -420,6 +420,7 @@ local TouchMenu = FocusManager:new{
     tab_item_table = nil, -- mandatory
     -- for returning in multi-level menus
     item_table_stack = nil,
+    parent_id = nil,
     item_table = nil,
     item_height = Size.item.height_large,
     bordersize = Size.border.window,
@@ -757,6 +758,7 @@ function TouchMenu:switchMenuTab(tab_num)
     self.page = 1
     -- clear item table stack
     self.item_table_stack = {}
+    self.parent_id = nil
     self.cur_tab = tab_num
     self.item_table = self.tab_item_table[tab_num]
     self:updateItems()
@@ -766,6 +768,16 @@ function TouchMenu:backToUpperMenu()
     if #self.item_table_stack ~= 0 then
         self.item_table = table.remove(self.item_table_stack)
         self.page = 1
+        if self.parent_id then
+            self:_recalculatePageLayout() -- we need an accurate self.perpage
+            for i = 1, #self.item_table do
+                if self.item_table[i].menu_item_id == self.parent_id then
+                    self.page = math.floor( (i - 1) / self.perpage ) + 1
+                    break
+                end
+            end
+            self.parent_id = nil
+        end
         self:updateItems()
     else
         self:closeMenu()
@@ -857,6 +869,7 @@ function TouchMenu:onMenuSelect(item)
             end
         else
             table.insert(self.item_table_stack, self.item_table)
+            self.parent_id = item.menu_item_id
             self.item_table = sub_item_table
             self.page = 1
             if self.item_table.open_on_menu_item_id_func then