Very occasionally I see a mismatch between server and gui model positions when dragging the model from one place to another, see screenshot.
In the screenshot, the wireframe moves as I drag the model with the mouse but the solid model remains in the same position. Not sure if it's something introduced in this branch or the issue is already present in default. Need to test more.
This branch has been merged with default and installs to gazebo_1.9 now, but I've just reproduced it. Another symptom is that the client appears unable to add new visuals once it gets into this state. If I insert a new model, it's visuals will not be created. I can see the contacts from models, and I can see everything if I open a new gzclient.