Window Management

Quick Reference

var window = new HermesWindow()
    .SetTitle("My App")
    .SetSize(1024, 768)
    .SetMinSize(640, 480)
    .Center()
    .SetResizable(true)
    .RememberWindowState();

Configuration

All configuration methods use a fluent API and must be called before Show() or WaitForClose().

Method	Description
SetTitle(string)	Window title
SetSize(int, int)	Initial size in pixels
SetPosition(int, int)	Initial position
Center()	Center on screen
SetResizable(bool)	Allow resizing
SetMinSize(int, int)	Minimum size constraint
SetMaxSize(int, int)	Maximum size constraint
SetCustomTitleBar(bool)	Enable custom title bar mode
RememberWindowState(string?)	Persist position, size, and maximized state across launches
SetTheme(HermesWindowTheme)	Light or dark window chrome and WebView (default: follow the system)

Window State

Control window state at runtime:

window.MaximizeWindow();
window.MinimizeWindow();
window.RestoreWindow();
window.ToggleMaximize();

bool maximized = window.IsMaximized;

Light and Dark Appearance

HermesWindowTheme sets whether the native window chrome and the WebView use the light or dark appearance. System (the default) follows the operating system; Light and Dark override it. Match it to your app's own theme so the native parts of the window stay readable, for example the macOS traffic lights on a light app theme.

var window = new HermesWindow()
    .SetTheme(HermesWindowTheme.Light);

// Later, when the user switches the app's theme:
window.Theme = HermesWindowTheme.Dark;

Theme can be set at any time and from any thread; Hermes applies the change on the UI thread. In a Blazor app, set the initial value with options.Theme in ConfigureWindow, and inject HermesWindow to change it at runtime:

@inject HermesWindow Window

@code {
    private void OnDarkModeChanged(bool dark) =>
        Window.Theme = dark ? HermesWindowTheme.Dark : HermesWindowTheme.Light;
}

Platform	Effect
macOS	Window appearance, including the title bar and traffic lights; the WebView's prefers-color-scheme follows
Windows	Title bar colors and the WebView2 preferred color scheme
Linux	Ignored for now; the window follows the GTK theme

Close Request Handling

OnCloseRequested lets you intercept the close button click before the window closes. This is useful for prompting the user about unsaved changes or running cleanup logic.

The handler returns a Task<bool>: return true to allow the close, or false to cancel it.

var window = new HermesWindow()
    .SetTitle("My Editor")
    .SetSize(1024, 768)
    .OnCloseRequested(async () =>
    {
        if (!hasUnsavedChanges)
            return true;

        var shouldClose = await PromptSaveChangesAsync();
        return shouldClose;
    })
    .LoadHtml("<h1>Hello</h1>");

window.WaitForClose();

In a Blazor application, you can wire this up from a root component:

@inject HermesWindow Window

@code {
    protected override void OnInitialized()
    {
        Window.OnCloseRequested(OnCloseRequestedAsync);
    }

    private async Task<bool> OnCloseRequestedAsync()
    {
        if (!IsDirty)
            return true;

        ShowConfirmDialog = true;
        await InvokeAsync(StateHasChanged);

        // Wait for the user's decision
        return await _closeDecision.Task;
    }
}

OnCloseRequested vs OnClosing

OnCloseRequested fires before the window closes and can prevent it. OnClosing fires after the close is confirmed and cannot cancel it. Use OnCloseRequested for save prompts; use OnClosing for final cleanup.

Next Steps

• HermesWindow API - full API reference
• Custom Title Bars - platform-specific title bar behavior
• Dialogs - native file dialogs