Design consideration for desktop application object

I am involved in a project to build an application from scratch. In past i have used t开发者_开发问答he application objects as provided by some UI frameworks (Qt, MFC etc.). Now I require to design the application class.

Mine is a desktop application that shall run on Windows, Linux. I am collecting other specific requirements. But I want to know

In general, what are design considerations for an application class?

Little background for understanding. Most of the desktop application have an entry point, where the application starts. This is generally encapsulated in an Application Class (QApplication in Qt, CWinApp in MFC etc.). These classes need to cater various requirements of the application. I want to know design considerations for such a class.

Since you want to support multiple platforms then i think Java is a good option. But im not sure what do you mean by "Application Class"