The toggle button in the tool menu lacked distinction from the tools in the menu.
I've made the following changes:
- added subtle differences to the look of the button to make it visually distinct from the tools in the tool menu
- moved the arrow icon out of the vertical alignment of the tool icons in the menu
- added a slight animation to show the change to the icon's orientation between the two states
- gave the button a hover state for mouse users
- made the button slightly larger for touch users
- fixed alignment issues of the icon caused by rotating the arrow
See my "before" and "after" screenshots for visual representation of the changes.