Hideable Sitefinity Content Block Widget

HideableContentBlock.cs

public class HideableContentBlock : ContentBlock
{
	protected override void Render(System.Web.UI.HtmlTextWriter writer)
	{
		// always render in page editor
		if (this.IsDesignMode() || this.IsPreviewMode())
		{
			base.Render(writer);
			return;
		}

		// exit if parameters are found
		var urlParam = this.GetUrlParameters();
		if (urlParam != null && urlParam.Length > 0) return;

		base.Render(writer);
	}
}

Be sure to include the namespace System.Web.UI