[Plugin: Meta Box] Feature Request: Select List – OPTION GROUP (OPTGROUP)

I’ve put a solution to this problem in place, you may think of a better one:

$html	 = "<select class='rwmb-select'{$name}{$id}{$disabled}>";

			$current_optgroup = "";
			foreach ( $field['options'] as $key => $value )
			{
				if( $value == "optgroup" )
				{
					if( ($current_optgroup != $key) && (!empty($current_optgroup)) )
					{
						//vmodha: If there was a previously opened optgroup then close it before opening a new one.
						$html		.= '</optgroup>';
					}
					$current_optgroup = $key;
					$html		.= '<optgroup label="' . $key  . '">';
					continue;
				}

				$selected	 = selected( in_array( $key, $meta ), true, false );
				$html		.= "<option value='{$key}'{$selected}>{$value}</option>";
			}

			if( !empty($current_optgroup) )
			{
				$html		.= '</optgroup>';
			}

			$html	.= "</select>";

You simply need to provide the optgroup title in the array KEY and set the VALUE of the array as ‘optgroup’.

'Brands And Stuff' => 'optgroup',
							'Brands' => 'Brands',
				'Agency Partners' => 'Agency Partners',
				'Second Group' => 'optgroup',
				'Production Partners' => 'Production Partners',
				'DMS' => 'DMS'

Simple but you may think up something better.

Cheers
vmodha