The screenshot shows the new camera controls (bottom left of the main area) and the game area reference controls (bottom right of the main area). They are both transparent, and their visibilities are toggled via the buttons in the main menu on left. The game area reference controls are used to show what area of the world will be initially visible in a canvas of a certain size, representing it as a black rectangle in the main view.
In the top right of the screen is the minimap which shows a bigger part of the (theoretically infinite) world. On the minimap, the black rectangle represents the area of the world that is shown on the main drawing area (note that the camera is rotated in the screenshot, resulting in a rotated rectangle on the minimap). The minimap camera automatically moves to always fully contain the area that the main camera is showing.
The screenshot also shows the ability to drag and select multiple entities at once: the green rectangle is the selection area.