Allow to focus readonly form elements (like other browsers do, partial revert of the commits for 159682),
which makes it possible to copy their text, too (for tomj on irc).
On the other hand, don't allow Ctrl+X and Ctrl+V to work in such widgets.
Will backport for 4.3.3.
BUG: 203069
CCBUG: 159682

svn path=/trunk/KDE/kdelibs/; revision=1032808