Marc,
I give up with Safari & Dragmath ... Safari (4) works fine with the other code in plugins but stops responding after you insert notation with DragMath. Because HTMLArea does not even render Safari there is not much to do but do you know a tool for debugging Safari - it is either a Safari, java or TinyMCE bug but I don't know which one.
One interesting note today was that forum strips style tags. I was testing a demo site and surprisingly moodle (1.9.5+) changes style="vertical-align: middle;" to style="middle;" (in source) in forum posts and when you edit the content this "wrong style" is totally cut away. It does not happen with summaries etc. I did not study the code deeper to find out where this happens but I added a class="texrender" to google tex tags and math theme css with vertical alinment to middle and equations are aligned correct. With styles dropdown list it is possible to give also other classes like AM/Edit before (in TinyMCE). A couple of tiny bugs are still left but Google Chart API tex renderer plugin looks rather good now and I can continue with these other formats.
A public demo with student access (Test forum available with Googletex button) and a jQuery ThemeRoller switcher demo inside the plugin is in http://korpelainen.net/gmoodle with username test and password test. This plugin is using jQuery because I found it much faster than yui if we need to have multiple tabs with hundreds of small images and jQuery tabs use ajax to load only the selected tab (file) - not all images - and save a lot of IE users time. New users may be surprised about Dragmath loading quite a long time at first but it is only java...
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