Workaround for Terminal.Gui OptionSelector Space-cycling and initial visual desync

optionselector-space-workaround.cs

// Workaround for OptionSelector Space-cycling and initial visual desync.
//
// Problem: OptionSelector always calls Cycle() when Space is pressed on the
// currently selected CheckBox. There's no way to disable this. Additionally,
// OptionSelector defaults Value=0 but doesn't call UpdateChecked(), so child
// CheckBoxes are visually unchecked even though the selector thinks the first
// item is selected.
//
// Solution: Intercept Space at the app keyboard level, suppress it entirely
// for OptionSelectors, and manually set the value or force the visual sync.

// In your app setup:
app.Keyboard.KeyDown += OnKeyDown;

// Key handler (Enter/Esc are wizard-specific; the Space case is the workaround)
private void OnKeyDown(object? sender, Key key)
{
    if (sender is not IKeyboard { App.TopRunnableView: WizardMainView wizard })
    {
        return;
    }

    // ... other key handling ...

    if (key == Key.Space)
    {
        SelectFocusedOption(wizard);
        key.Handled = true;
    }
}

// Select the focused option without triggering Cycle().
// When the value is already correct but CheckBoxes are visually out of sync
// (initial load where Value=0 is the default but no CheckBox is checked),
// UpdateChecked() forces the visual state to match.
private void SelectFocusedOption(View root)
{
    var selector = FindFocusedOptionSelector(root);
    if (selector is not { Focused: CheckBox focused })
    {
        return;
    }

    var targetValue = selector.GetCheckBoxValue(focused);

    if (selector.Value != targetValue)
    {
        selector.Value = targetValue;
    }
    else
    {
        // Value matches but CheckBox may be unchecked visually
        selector.UpdateChecked();
    }
}

// Recursive tree walk to find the OptionSelector that currently has focus.
// HasFocus propagates up the hierarchy, so the OptionSelector itself reports
// HasFocus=true when any child CheckBox is focused.
private static OptionSelector? FindFocusedOptionSelector(View root)
{
    foreach (var child in root.SubViews)
    {
        if (child is OptionSelector { HasFocus: true } selector)
        {
            return selector;
        }

        if (FindFocusedOptionSelector(child) is { } found)
        {
            return found;
        }
    }

    return null;
}