I'm experiencing this as well under MacOS Sierra. Additionally, I am finding that at times I am unable to scroll in either the Query Tool window or the results grid. Closing and re-opening pgAdmin 4 restores functionality.
Under certain conditions (and unfortunately, I cannot say what exactly triggers it, but it happens often), the context menu doesn’t work anymore.
I can open it with a right-click on an element in the browser pane on the left side, I can even open sub-menus by pointing at them, but when I want to click on a menu item, nothing happens, the menu simply stays open (as if I hadn’t clicked at all).
It is still possible to trigger the actions from the menu bar, but the context menu is (and stays) unusable until I restart the application.
