This can be themed/styled and also workaround the Safari/WebKit bug mentioned in #1728.
See also: piwikHelper.windowModal().
The popover showing for Widget delete confirmation (see piwikHelper.windowModal JS) should be reused in other deletion confirmation such as
user deletion, site deletion, goal deletion
@vipsoft: are you still working on that item? If not, I would do so ;)
(In ) refs #2123
Last 2 items are:
Kuddos Stefan for reducing our technical debt!
(In ) refs #2123 replaced js confirm with dialog for goal deletion
(In ) refs #2123 replaced last confirm with dialog (site deletion)