Tried this with Safari and FireFox. Also tried with IE in a VM, but not sure that's so conclusive. All three were broken in slightly different ways. Reporting on Safari here, though.

• When I left-click the rectangle on the right side of a subtask list (what is that rectangle for, anyway?) Safari changes my cursor to the context-menu cursor. It stays that way until I hit ESC. Things are otherwise normal

• When I right-click (or control-click) inside that rectangle, I get Safari's regular context menu (e.g. with "Back" and "Reload Page")

• When I right-click (or control-click) anywhere outside that rectangle, it will bring up the Redmine context menu, but it seems only to notice my mouse position when I either click to select a menu item, or, for an instant, when I press the control key again. That makes it impossible to select items in submenus until you notice that you can get the menu to wake up when you press control, because the submenu won't be displayed otherwise.

I tried to get some of the information requested at http://www.redmine.org/wiki/redmine/SubmittingBugs, but you may have seen my other issue. It's a fresh installation of the latest redmine, MySQL, Rails, etc.