I noticed that justified paragraphs are left aligned when they contain a "smart resized" image. Here is an example:
HTML in Jooma editor:
<p style="text-align: justify;"><img style="margin: 7px; float: left;" src="images/eventgallery/Historische_Bilder/009_1958_02.jpg" alt="009 1958 02" />Um es kurz zu machen: einen tieferen Einstieg in den geschichtlichen Abriss über Wesen [...]</p>
What is sent to the browser after SmartResizer resized that image:
<p style="text-align: justify;"><a href="images/eventgallery/Historische_Bilder/009_1958_02.jpg" style="background:none;" onclick="return hs.expand(this)" ><img style="margin: 7px; float: left;" src="images/eventgallery/Historische_Bilder/smart_thumbs/009_1958_02_thumb_medium400_0.jpg" alt="009 1958 02" /></a>
<div class="highslide-caption">009 1958 02</div>Um es kurz zu machen: einen [...]</p>
The problem is the div within the p-tag which is not allowed and causes browsers to automatically close the p-tag. A span-tag for example would work with an p-tag. I changed this in smartreszier.php line 614 and now it is working for me.
Just wanted to let you know in case you want to change it for the official version, too, as most if not all pictures will be within a paragraph.