.ajax-progress--fullscreen z-index should be higher than .ui-dialog when triggered in a modal.

OS: Ubuntu 18.04.4 LTS
PHP Version: 7
Drupal Version: 8.8.x

Problem/Motivation

- The .ajax-progress--fullscreen z-index is set to 1000 in '/claro/css/components/ajax-progress.module.css', line 141.
- The .ui-dialog z-index is set to 1260 in '/claro/css/components/ajax-progress.module.css?', line 14.
- For people opening a single dialog, this is fine, as the .ajax-progress--fullscreen is replaced by the .ui-widget-overlay and the dialog itself. However, when the .ajax-progress--fullscreen is triggered from an already open dialog, the current dialog remains exposed for accidental multiple submissions at z-index 1260 (until it is replaced by the new dialog) as the loader is running behind it at index 1000.

Proposed resolution

Increase the z-index of the .ajax-progress--fullscreen class above that of the .ui-dialog class.

Currently .ui-dialog have a z-index of 1260. As suggested in #9, we can have z-index as 1500.

--jui-dialog-z-index: 1260;
.ui-dialog {
  z-index: var(--jui-dialog-z-index);
}

Thank you for Claro and all of the hard work going into it!!!

Jeremy