Window is the top-level control in Avalonia. The default application templates create a single Window called MainWindow. You can create additional windows from templates too:

  1. Right click the folder in Solution Explorer that you'd like to add the window to
  2. Select the Add -> New Item menu item
  3. In the dialog that appears, navigate to the "Avalonia" section in the category tree
  4. Select "Window (Avalonia)"
  5. Enter your window name under "Name"
  6. Click the "Add" button

Run this command replacing [namespace] with the namespace you'd like to create the window in and [name] with the name of the window.

dotnet new avalonia.window -na [namespace] -n [name]

For more information see the .NET core templates repository.

A window consists of two parts: a XAML file (e.g. MainWindow.xaml) and a codebehind file (e.g. MainWindow.xaml.cs). The codebehind defines a .NET class which represents the window.

For more information and examples, see the Window control.