Hi Hjalmar,

There is no easy way to do this, however, if you're not using personalization or display options you could use an IList<ContentReference> instead which supports mutliselect.

Cool, that worked!

Is it possible to make an IList<T> not look horrible in the CMS if I have many AllowedTypes?

Have you tried using a base class, or an interface, as argument for your AllowedTypes attribute?

Probably the easy (or at least easiest) option is just to hide the whole header/allowed types section. You could achieve that with the following:

Add an editor descriptor:

[EditorDescriptorRegistration(EditorDescriptorBehavior = EditorDescriptorBehavior.ExtendBase, TargetType = typeof(IList<ContentReference>), UIHint = UiHint)]
public class HideAllowedTypesEditorDescriptor : EditorDescriptor
{
    public const string UiHint = "HideAllowedTypes";

    public override void ModifyMetadata(ExtendedMetadata metadata, IEnumerable<Attribute> attributes)
    {
        base.ModifyMetadata(metadata, attributes);
        metadata.EditorConfiguration.Add("class", "hide-header");
    }
}

Add the following to your module.config (or create it if it doesn't exist):

<?xml version="1.0" encoding="utf-8"?>
<module>
  <clientResources>
    <add name="epi-cms.widgets.base" path="~/ClientResources/Styles/HideHeader.css" resourceType="Style" />
  </clientResources>
</module>

Add the styling (should be at the path in you module.config):

.epi-content-area-wrapper.hide-header {
    padding-top: 0;
}

.epi-content-area-wrapper.hide-header .epi-content-area-header-block {
    display: none;
}

Now you can use it on any IList<ContentReference>:

[UIHint(HideAllowedTypesEditorDescriptor.UiHint)]
public virtual IList<ContentReference> Example { get; set; }