Fix Menu focus. (#850)

Bug:https://github.com/ArthurSonzogni/FTXUI/issues/841

CHANGELOG.md

@@ -34,6 +34,7 @@ current (development)
 - Bugfix: Propertly restore cursor shape on exit. See #792.
 - Bugfix: Fix cursor position in when in the last column. See #831.
 - Bugfix: Fix `ResizeableSplit` keyboard navigation. Fixed by #842.
+- Bugfix: Fix `Menu` focus. See #841
 
 ### Dom
 - Feature: Add `hscroll_indicator`. It display an horizontal indicator

src/ftxui/component/menu.cpp

@@ -131,8 +131,9 @@ class MenuBase : public ComponentBase, public MenuOption {
           is_focused,
       };
 
-      auto focus_management =
-          is_menu_focused && (selected_focus_ == i) ? focus : nothing;
+      auto focus_management = (selected_focus_ != i) ? nothing
+                              : is_menu_focused      ? focus
+                                                     : select;
 
       const Element element =
           (entries_option.transform ? entries_option.transform