Filament: Form with Textarea Content Preview

To create this action, we first have to create our Fields:

app/Filament/Resources/PostResource.php

// ...
Forms\Components\RichEditor::make('rich_content')
    ->required()
    ->columnSpanFull(),
Forms\Components\Textarea::make('markdown_content')
    ->required()
    ->columnSpanFull(),
// ...

Currently, they do nothing but store the content. From here, we want to add a new action with slideOver to our form:

app/Filament/Resources/PostResource.php

// ...
Forms\Components\RichEditor::make('rich_content')
    ->required()
    ->columnSpanFull()
    ->hintAction(
        fn(Forms\Get $get) => Forms\Components\Actions\Action::make('previewContent')
            ->slideOver()
// ....