area of the terminal display widget after the content is scrolled with QWidget::scroll() :

- Set the left edge of the scrolled rect to 0 (instead of the left margin used when
drawing the text)
- Set the right edge of the scrolled rect to width() - width of scroll bar - 1.  If the
right edge of the scrolled rect touches the scroll bar then a full repaint of the widget
is triggered.

These changes are based on experimentation.  I haven't had time to look into Qt to
find out exactly what changed between Qt 4.3 and 4.4.

Update comments to reflect changes and add a mention of Qt's QT_FLUSH_PAINT repaint
monitoring facility.

CCBUG: 158523

svn path=/trunk/KDE/kdebase/apps/konsole/; revision=783788