Skip to main content

Window

Window is a top-level ContentControl that represents an operating-system window. It provides the title bar, icon, and system chrome (close, minimize, maximize buttons) that your users expect from a desktop application.

You do not usually create instances of Window directly. Instead, you subclass Window for each type of window your application needs.

tip

Window is only available on desktop platforms (Windows, macOS, Linux). If you are targeting mobile or browser, use UserControl with a navigation framework instead.

Common properties​

PropertyTypeDescription
TitlestringThe text displayed in the title bar.
IconWindowIconThe icon displayed in the title bar and taskbar.
SizeToContentSizeToContentControls whether the window auto-sizes to fit its content horizontally, vertically, or both.
WindowStateWindowStateGets or sets whether the window is Normal, Minimized, Maximized, or FullScreen.
CanResizeboolGets or sets whether the user can resize the window.
ShowInTaskbarboolGets or sets whether the window appears in the operating-system taskbar.
TopmostboolGets or sets whether the window stays above all other windows.
SystemDecorationsSystemDecorationsControls the window chrome (title bar and borders). Set to None for a borderless window.
ExtendClientAreaToDecorationsHintboolWhen true, your content extends into the title bar area, allowing custom chrome.

Show, hide, and close a window​

You can show a window by calling the Show method:

var window = new MyWindow();
window.Show();

You can close a window by calling Close. This has the same effect as when a user clicks the window's close button:

window.Close();
warning

Once a window has been closed, it cannot be shown again. Calling Show on a closed window will throw an exception. If you need to show the same window again later, call Hide instead of Close.

window.Hide();

// You can show the window again later.
window.Show();

See also Prevent a window from closing.

Show a window as a dialog​

You can show a window as a modal dialog by calling ShowDialog. This method requires you to pass an owner window so the system knows which window the dialog belongs to:

// "this" is the current Window instance.
// You can also obtain the main window from
// Application.ApplicationLifetime cast to IClassicDesktopStyleApplicationLifetime.
var ownerWindow = this;
var dialog = new MyWindow();
dialog.ShowDialog(ownerWindow);

ShowDialog returns a Task, so you can await it to wait until the dialog is closed:

var dialog = new MyWindow();
await dialog.ShowDialog(ownerWindow);

Return a result from a dialog​

Your dialog can return a result by passing a value to the Close method. The caller reads the result through the generic ShowDialog<T> overload:

public class MyDialog : Window
{
    public MyDialog()
    {
        InitializeComponent();
    }

    private void OkButton_Click(object? sender, EventArgs e)
    {
        Close("OK Clicked!");
    }
}
var dialog = new MyDialog();

// The result is a string, so use ShowDialog<string>.
var result = await dialog.ShowDialog<string>(ownerWindow);

Prevent a window from closing​

You can prevent a window from closing by handling the Closing event and setting e.Cancel = true:

window.Closing += (s, e) =>
{
    e.Cancel = true;
};

A common pattern is to hide the window instead of closing it so you can show it again later:

window.Closing += (s, e) =>
{
    ((Window)s!).Hide();
    e.Cancel = true;
};

Practical notes​

  • Startup window. Your application's main window is typically set in App.axaml.cs by assigning MainWindow on the IClassicDesktopStyleApplicationLifetime. See Main window for details.
  • Multiple windows. You can open as many windows as you need by creating new instances and calling Show. Each window runs independently within the same application.
  • Positioning. Use the Position property (of type PixelPoint) to set the window's screen coordinates, or set WindowStartupLocation to CenterScreen or CenterOwner.
  • Closing behavior. When the last window closes, your application exits by default. You can change this by setting ShutdownMode on the application lifetime.

See also​

On this page