Editor seems to use the class 'contextual-toolbar-tab' on it's 'toolbar-tab' in-order assign float:right. Work on #2724819: Create experimental module for place block on any page feature also tried to use the class as it seems generic.
[2724819#31] however, once both buttons where using it clicking on 'place block' all contextual links (Edit's One state) do become active.
'contextual-toolbar-tab' (in contextual.toolbar.js) should use that new Editor class.
Also, should not that specific trigger 'visually show all contextual links' behaviour should be moved into Editor.module. it's seem odd to be in contextual.module