It is common for a commercial product to be composed of several Qt projects. We regularly encountered this practice in this book-for example, an application composed of a core project and a GUI project. The Qt subdirs project is a nice way of handling inter-dependent projects within the same application.

However, when your product grows up, you'll want to open some unrelated projects in Qt Creator. In this case, you should use a session. A session is a complete snapshot of your workspace in Qt Creator. You can easily create a new session from File | Session Manager | New. Do not forget to switch to the new session. For example, you can create a session "Mastering Qt5" and load all project examples in a common workspace.

The sessions are useful when you need to quickly switch between two different workspaces. The following items in Qt Creator will be automatically saved in the session: