The custom editor tools button on the toolbar currently has no icon, and no tooltip when hovered over. These need to be added.

1. Install Unity
2. Create a new project with any settings
3. When the project has loaded, look at the custom tools context menu button on the toolbar

Expected result:
Button has an icon and displays a tooltip when hovered over.

Actual result:
The button has no icon, and no tooltip is displayed when the mouse is hovered over it.

Occurs on 2019.1.0a10, which is the first version in which the feature was introduced.

Tested on Windows.