Throbbers showing within dropbuttons jump to next line

I think this is a hard one to test, and until #2830584: Use modals for creating, updating, and deleting workflows, with a new DialogFormTrait lands I don't think there are any throbblers on drop buttons in core, but it fixes the issue.

Thanks @timmillwood!

I have actually seen this before somewhere in core, not sure where. Probably the Views UI or something. In any case, tagging for the frontend committers.

Thanks to @Manuel Garcia!

Views uses a full-screen throbber, as added in #2207695: Expand the throbber API to include a 'full screen' option, from what I can see. Although we'll soon have somewhere in core doing it, when #2830584: Use modals for creating, updating, and deleting workflows, with a new DialogFormTrait gets in. ;)

I tested this on simplytest, using this patch and the one in #2830584: Use modals for creating, updating, and deleting workflows, with a new DialogFormTrait. The throbber stays on the same line now, so looks good to me!

Opened #2914519: Update the design for "loading…" buttons that show a spinner animation as a followup to improve the design of this thing.

Removed on the commit the px from the 0 value.

Committed 0540b0e and pushed to 8.5.x. Thanks!

This change causes the ajax progress content to be displayed on top of other content. This becomes very apparent when working with the Paragraphs module:

I suggest this change is reverted until we have determined a solution that works for all ajax progress indicators.

I have also filed a bug report at #2935593: Ajax progress throbber displays on top of other content