Limit the size of the text in the error dialog box

When apport fails to report a crash, it displays a dialog box to the user with a full dump of whatever went wrong. This dialog box should be redesigned so that its size is always reasonable, or at least with a "close" button near the top, as otherwise it can create a really huge window which cannot easily be closed for non-savvy users. Attached is a screenshot of such a situation.

(also, the huge size breaks the gnome-shell Activity screen, but that's not our problem :P )