fix context menus in ie10 not accessible

[``* `#16028 ` context menus in ie10 not accessible``](http://www.openproject.org/work_packages/16028)

I am not sure how we should go on with this. IE10 allows only for specific elements to be focused (inputs, anchors), and not divs. I'll look into the focusing divs, not sure at the moment. This is the reason I didn't touch the right menu (the one with queries), as it focuses on divs and if I change it to anchors, it'll look uglier.
Please put all code layout specific changes in a separate commit.