Font menu: show only 5 items per page

To get more room below to see how the text looks
with the selected font.

frontend/apps/reader/modules/readerfont.lua

@@ -309,6 +309,9 @@ function ReaderFont:makeDefault(face, touchmenu_instance)
 end
 
 function ReaderFont:addToMainMenu(menu_items)
+    -- Have TouchMenu show half of the usual nb of items, so we
+    -- have more room to see how the text looks with that font
+    self.face_table.max_per_page = 5
     -- insert table to main reader menu
     menu_items.change_font = {
         text = self.font_menu_title,

frontend/ui/widget/touchmenu.lua

@@ -379,7 +379,7 @@ local TouchMenu = FocusManager:new{
     width = nil,
     height = nil,
     page = 1,
-    max_per_page = 10,
+    max_per_page_default = 10,
     -- for UIManager:setDirty
     show_parent = nil,
     cur_tab = -1,
@@ -560,8 +560,9 @@ function TouchMenu:_recalculatePageLayout()
 
     local item_list_content_height = content_height - footer_height
     self.perpage = math.floor(item_list_content_height / self.item_height)
-    if self.perpage > self.max_per_page then
-        self.perpage = self.max_per_page
+    local max_per_page = self.item_table.max_per_page or self.max_per_page_default
+    if self.perpage > max_per_page then
+        self.perpage = max_per_page
     end
 
     self.page_num = math.ceil(#self.item_table / self.perpage)