Dialog not always positioned correctly

Problem/Motivation

Dialogs are sometimes positioned outside the viewport, so that the user has to scroll down to actually see the dialog. This happens with e.g. the Conflict → module when the page is a long one (see video attached). At first I thought this was an issue with the Conflict module itself, but it works just fine with Claro. I noticed that Claro has position: absolute; for the .ui-dialog element (see issue 3191527 → ), whereas when using Gin, position is not set anywhere and the element gets position: relative; as an inline style.

When I set position: absolute; in Gin styles, the dialog is positioned correctly and is visible in the viewport.

Steps to reproduce

1. Install Conflict module.
2. Create a node with a long body, so that the page is stretched down way past the viewport bottom.
3. Open the node in two tabs, make a change to the body in one tab and save.
4. Go to the other tab, make another kind of change in the body and try to save.
5. You should now see the overlay but not the dialog, until you scroll down.

See the attached video for an example.

Proposed resolution

Set position: absolute for the .ui-dialog element like in Claro (see issue 3191527 → ).