登录 - 将用户数据传递到新窗口/将其存储为静态信息？ [桌面应用]

I'm trying to make a desktop C++ application (using Qt, if it matters for this problem) that features an authentication system. It can be used by ONE user at a time. When the application starts, a log in form will allow the user to type his username and password. After logging in, a new window will be displayed. My question is: should I pass the user's ID and/or username to the next window [as a constructor parameter?] (and use such system for other windows as well) OR would it be ok (I'd much rather prefer this) to store this data in the static fields of a class and access it from everywhere? [doesn't sound too bad since I only allow ONE user to be logged in at any time]. I should also mention that I'll be trying to use the Model-View-Controller pattern.I'm trying to make a desktop C++ application (u