Nesting optgroups in a dropdownlist/select

Question

I have created a customer c# DropDownList control that can render out it's contents are optgroups (Not from scratch, I edited some code found on the internet, although I do understand exactly what it's doing), and it works fine.

However, I have now come across a situation where I need to have two levels of indentation in my dropdown, i.e.

<select>    <optgroup label="Level One">      <option> A.1 </option>      <optgroup label="Level Two">        <option> A.B.1 </option>      </optgroup>      <option> A.2 </option>    </optgroup>  </select>

However, in the example snippet above, it is rendering as if Level Two was at the same amount of indentation as Level One.

Is there a way to produce the nested optgroup behavior I am looking for?

Answer 1

The HTML spec here is really broken. It should allow nested optgroups and recommend user agents render them as nested menus. Instead, only one optgroup level is allowed. However, they do have to say the following on the subject:

Note. Implementors are advised that future versions of HTML may extend the grouping mechanism to allow for nested groups (i.e., OPTGROUP elements may nest). This will allow authors to represent a richer hierarchy of choices.

And user agents could start using submenus to render optgoups instead of displaying titles before the first option element in an optgroup as they do now.