As we added GUI features to Gazebo, the look and feel began to seem a bit disjointed. We lacked an overarching design spec for the interface, one that provided clear standards for padding, color, line weight, and so on.
We concluded that Material Design would suit our needs, offering well-documented guidelines and options. The new Material Design-focused Gazebo GUI is still in the prototype phase, but here is a mock-up demonstrating the new visual cues that identify when simulation is paused or playing. In user studies, the play/pause state was a common source of confusion.One challenge we face is the potentially homogeneous look and feel shared with other applications that make use of Material Design. To help differentiate Gazebo from Google products, we are using a custom icon set, and will tailor the design specs to meet our own needs.