You can use Settings to share data between different Windows/Controls and even save application data when closing/starting an application.
The .NET Framework allows you to create and access values that are persisted between application execution sessions. These values are called settings. Settings can represent user preferences, or valuable information the application needs to use. For example, you might create a series of settings that store user preferences for the color scheme of an application. Or you might store the connection string that specifies a database that your application uses. Settings allow you to both persist information that is critical to the application outside of the code, and to create profiles that store the preferences of individual users.
You can save a Setting in any Window:
Properties.Settings.Default.mySetting = true;
Properties.Settings.Default.Save();
You can read/use a setting in any Window:
this.Property = Properties.Settings.Default.mySetting;