[Inheritance Margin] Mouse sets focus to the margin icon

[davkean]

Version Used:
Version 16.10.0 Preview 3.0 [31224.71.main]

Unlike all other menus/toolbar buttons/lightbulb, clicking the Inheritance Margin sets focus to it, meaning that pushing escape after dropping the menu leaves you on it instead of the editor.
Steps to Reproduce:

1. Click on the Margin icon
2. When the menu shows, press ESC

Expected Behavior:
Focus to be set on the editor

Actual Behavior:
Focus is set on the margin icon itself.