A very very old bug and annoyance: tooltips with very long content without
spaces (e.g. long URLs or gibberish data) would just cut off and leave an
un-styled right border going over the widget's constrained space.
Because of an additional bug (still unsolved), this was never properly
addressed because solutions attempted didn't work.
The workaround for the secondary bug allows for word-break to now work and this
primary problem to be resolved.
This would interfere with implementing thin scrollbars.
Almost all widgets provide a non-overridable size for scrollbar buttons, so it
makes no sense to specify min size for them. It is probably(?) a layout bug that
min size properties can override the value returned by GetMinimumWidgetSize
even if aIsOverridable is set to false, but removing this rule is simpler than
locating and fixing the issue in layout code ;)
This changes the toolkit theme for Linux and Windows (Mac already did this) to
style the input textbox on the findbar with -moz-appearance:none so as to give
us styling control (as opposed to using a native widget style) and apply a
neutral style to it.
Also ensures Mac remains readable in case of poorly contrasting text.
