The JavaScript drop-down menus appears on the left edge in the window, rather than where they should in 10.5.1 Safari and latest WebKit nightly. Works fine in FireFox.
It appears that when re-visting the site and cached resources are used, the bug does not appear. It is likely to be in some way timing-related.
This could be another symptom of bug 7722.
The url at: swsoft.com does not exist anymore. When testing in Safari 17.4.1, the drop down menu works correctly at the web archive: https://web.archive.org/web/20080218162150/http://www.parallels.com/.
Created attachment 471061 [details] screenshot of web archive