**System Information**
Windows 10 64-bit, Nvidia gtx 570, Nvidia gtx 610
**Blender Version**
Broken: 2.77a, 9f39619 (latest 64-bit build)
Worked: -
**Short description of error**
Changing the diffuse colour of a material that is chosen as the render material for a hair particle system does not update the viewport colour of the particles unless that material is re-selected from the `material_slot` drop-down box in the particle system settings. This happens with the diffuse colour of a material in Blender Internal and the viewport colour of a material when using Cycles. This does not happen with 'Emitter' based particle systems, their viewport colour is updated immediately.
**Exact steps for others to reproduce the error**
Using: {F304277} (Increase particle number to see effect more visibly)
# Change the diffuse colour for the cube's material to red (or any colour)
# No colour change in hair particles is visible.
# In the particle settings for the cube re-select 'Material' from the `material_slot` drop-down box in the 'Render' panel.
# Particles now show the correct, updated colour.
The same steps can be repeated for Cycles, changing the material's 'Viewport Colour' instead.