bug#46025: 28.0.50; warning suppression buttons truncate warnings

[iarchivedmywholelife]

> Not sure what to do with warnings that show backtraces.

Perhaps we could do something similar to what the backtrace buffer does. After a certain length, ellide the warning with the ellipses, but make the ellipses expandable so the whole message can be seen. We could, optionally include a command to expand all.