**System Information**
macOS Sierra (10.12)
Intel Iris Pro
**Blender Version**
Broken: (2.78 80837d0)
Worked: (none)
**Short description of error**
Viewport panning and rotation is broken (movement is super bumpy) on macOS Sierra **only if** continuous grab is enabled.
**Exact steps for others to reproduce the error**
- in the settings panel under **Input**, activate the **Continuous Grab** option
- pan or rotate the 3D viewport (movement should be bumpy)
- by disabling **Continuous Grab**, viewport movement works as expected