These were broken-and-disabled in a previous PR because of 2 things:
- The Widgets' default vertical scrollbar size is now 2: this has to be reflected in these tests, in order to benefit from their "regressions spotting" role
- As long as textual#581 ("Default versus User CSS") is not solved, the Widget's default CSS overrides the custom Widgets' own CSS.
The test now temporarily uses a more specific CSS selector in order to bypass this.