Also, specific to this branch (it doesn't happen in default), clicking on a moving object with the translate or rotate tool causes the display of that object to freeze. If you click the frozen object with the select tool, it will jump back to its moving state.
It seems a little better, but there still seems to be some problems with rolling objects. In a world file named wireframe.xml (download here), several spheres drop onto an inclined ramp. When selecting these spheres, the bounding box seems to have a different size each time I open that world in gazebo.
That said, I do still notice some complaints from libprotobuf when I select a link or light source from the ModelListWidget. Running gztopic list shows some strange message names at the end of the list: