Menu: don't underline items on touch devices (#3663)

First item would be underlined if the device is both Touch and Keys
capable (emulator, android, pocketboot...), which is not really
pretty. Delay that till Keys for focusing are really used.

frontend/ui/widget/menu.lua

@@ -368,8 +368,20 @@ function MenuItem:init()
     }
 end
 
-function MenuItem:onFocus()
-    self._underline_container.color = Blitbuffer.COLOR_BLACK
+function MenuItem:onFocus(initial_focus)
+    if Device:isTouchDevice() then
+        -- Devices which are Keys capable will get this onFocus called by
+        -- updateItems(), which will toggle the underline color of first item.
+        -- If the device is also Touch capable, let's not show the initial
+        -- underline for a prettier display (it will be shown only when keys
+        -- are used).
+        if not initial_focus or self.menu.did_focus_with_keys then
+            self._underline_container.color = Blitbuffer.COLOR_BLACK
+            self.menu.did_focus_with_keys = true
+        end
+    else
+        self._underline_container.color = Blitbuffer.COLOR_BLACK
+    end
     self.key_events = self.active_key_events
     return true
 end
@@ -830,7 +842,7 @@ function Menu:updateItems(select_number)
             -- reset focus manager accordingly
             self.selected = { x = 1, y = select_number }
             -- set focus to requested menu item
-            self.item_group[select_number]:onFocus()
+            self.item_group[select_number]:onFocus(true)
         end
         -- update page information
         self.page_info_text:setText(util.template(_("page %1 of %2"), self.page, self.page_num))