History On/Off extension has been updated.
There is one notable new feature in this version: you can now change the toolbar icon on the "options" page. For better support for different browser themes, you can select among several different colors for the icon: red, green, purple, yellow, beige and the default blue. To do this just go to extension's settings page and select the icon you like.
To access the options page:
1) Right-click on the extension's icon and select "Options":
2) And select the icon from the list: