Suggestions of the page picker in macro parameters display under the modal when used on the dashboard editor

How to reproduce:

• delete the XWiki.SharePage page, in order to disable the share page feature
• create a page using the dashboard template
• add a display or an include macro on the dashboard

Expected result:

• the page picker shows suggestions allowing to pick a page

Actual result:

• the suggestions of the picker are displayed under the modal of the macro:
  

Technically, when this works it seems that the xwiki.selectize.min.css sets the z-index of the dropdown to 1005. This CSS is not missing if the page contains the share page by email menu (which probably includes it because it needs it).
In the wysiwyg editing, this CSS is added by the CKEditor.EditSheet.

The macro modal should be including its own resources, in order to ensure that it works in all cases.