conditional os in UI xml, add system dialog file open on osx, check api format or error message when opening a document, per-char text wrap on NodeText, additional info on create doc dialog like working path

src/layout.cpp

@@ -48,6 +48,16 @@ bool LayoutManager::load(const char* path)
             LOG("Layout node without id");
             return false;
         }
+        if (auto os = current->Attribute("os"))
+        {
+            auto osv = split(os, ',');
+            if (std::find(osv.begin(), osv.end(), PP_OS) == osv.end())
+            {
+                LOG("Layout %s not for this os(%s), skipping", id_str, PP_OS)
+                current = current->NextSiblingElement("layout");
+                continue;
+            }
+        }
         //LOG("Parsing layout: %s", id_str);
         uint16_t id = const_hash(id_str);
         auto p = m_layouts.find(id);