Redmine

Should we only show Copy and Summary links when editing, only Edit and Summary links when copying and Edit and Copy links on the summary? I've tried and don't really like the way the menu changes when clicking its items.

What about deactivating those menu items. Something like grey them out? This would let the menu look the same on each link, but prevent the user from clicking edit if he is already in the edit mode.

Some idea how to use this could be the pointer-events setting in CSS.
See: http://css-tricks.com/pointer-events-current-nav/

There is just one regression: http://caniuse.com/#search=pointer-events
The IE support is not given.

Another idea would be to add this to the active menu item: onclick="return false"
Or just a jQuery function:

$(".currentMenu").click(function(){
return false;
});

Which suggests, that the current menu item get another class.

Maybe this idea is helpful.