Hitting carriage return cause the scrollbar to go at the end

[Perseides]

When using an html source that was previously generated by FCKEditor 2.3.1 with FCKEditor 2.6.3, hitting carriage return cause the scrollbar to go at the end of the box.

To reproduce, using Firefox 3, go to: ​http://www.fckeditor.net/demo, click the "Source" button, and paste this:

<p><font size="4"><font color="#008080"><strong><font color="#ff0000"><font color="#000080">Lorem</font></font></strong></font></font><font size="4"><font color="#008080"><strong><font color="#ff0000"><font color="#000080"><br /> </font></font></strong></font></font>Lorem ipsum dolor sit amet, consectetuer adipiscing elit. Nulla ac velit. Etiam adipiscing pede vitae elit. Nam turpis odio, tristique ac, semper ut, malesuada nec, mi. Vestibulum tempus turpis a eros. Aenean feugiat metus ac tortor. Cum sociis natoque penatibus et magnis dis parturient montes, nascetur ridiculus mus. In ultrices porttitor lorem. Ut posuere orci. Lorem ipsum dolor sit amet, consectetuer adipiscing elit. Suspendisse mattis.<font size="4"><font size="4"><font color="#008080"><strong><font color="#ff0000"><br /> <br /> Ipsum</font></strong></font></font><font size="4"><font color="#008080"><strong><br /> </strong></font></font></font>Lorem ipsum dolor sit amet, consectetuer adipiscing elit. Nulla ac velit. Etiam adipiscing pede vitae elit. Nam turpis odio, tristique ac, semper ut, malesuada nec, mi. Vestibulum tempus turpis a eros. Aenean feugiat metus ac tortor. Cum sociis natoque penatibus et magnis dis parturient montes, nascetur ridiculus mus. In ultrices porttitor lorem. Ut posuere orci. Lorem ipsum dolor sit amet, consectetuer adipiscing elit. Suspendisse mattis.<font size="4"><br /> <font size="4"><font color="#008080"><strong><br /> </strong></font></font></font><font size="4"><strong><font size="4" color="#000080"><font color="#ff00ff"><font color="#008080"><font color="#993366"><font color="#ff6600"><font color="#008080"><font color="#ff0000"><font color="#000080">Lorem</font></font></font></font></font></font></font></font></strong><strong><font size="4" color="#000080"><font color="#ff00ff"><font color="#008080"><font color="#993366"><font color="#ff6600"><font color="#008080"><font color="#ff0000"><br /> </font></font></font></font></font></font></font></strong></font>Lorem ipsum dolor sit amet, consectetuer adipiscing elit. Nulla ac velit. Etiam adipiscing pede vitae elit. Nam turpis odio, tristique ac, semper ut, malesuada nec, mi. Vestibulum tempus turpis a eros. Aenean feugiat metus ac tortor. Cum sociis natoque penatibus et magnis dis parturient montes, nascetur ridiculus mus. In ultrices porttitor lorem. Ut posuere orci. Lorem ipsum dolor sit amet, consectetuer adipiscing elit. Suspendisse mattis.<font size="4"><strong><font size="4" color="#000080"><font color="#ff00ff"><font color="#008080"><font color="#993366"><font color="#ff6600"><font color="#008080"><font color="#ff0000"><br /> </font></font></font></font></font></font></font></strong></font></p> <p>&nbsp;</p>

Then, click "Source" again. Go at the top of the red "Ipsum" title, and hit carriage return. The scrollbar will move to the end of the box.