PRE blocks don't extend to fill the available width and don't overflow

The block generated for PRE HTML element doesn't extend to fill the 
available width and doesn't overflow (narrow the window width to 
cause the content to overflow) as seen on the example I'm attaching 
("pre_block.html").

The 3rd example block also shows insertion of an extra empty line 
when non-breakable line start to overflow (seems the whitespace 
after BR element is not cleared).

-- 
Stanimir