Here's the logic behind the icon groupings, that was asked by a few as well:
Move/Fire Toggle 
Unit Actions: 
- Human Wave, Smoke, Starshell
Unit Handbook (F2)
Combat Actions: 
- Arty Dialog, Air Attack, Resolve Assault 
Movement Actions: 
- Load/Unload, Dig-in, Double Speed, Save APs for Unloading, Save APs for Firing 
Show Range Actions
- Command, Visibility, Hard/Soft Attack, Movement
Map Actions / Toggles:
- Thermometer, Unit Bases, Units, Objectives, Contours, Hex Grid, Rotate Map, Jump Map
Highlight Units:
- Anti-Aircraft, Artillery, Mine Clearing, Disrupted, Fixed, Moved, Fired, Low-on-Ammo, Spotted, Leaders, HQs, Organization
Add/Remove Units Dialogs
- Show arrived, Remove Units
Unit Orientations
- Turn Clockwise, Turn Counterclockwise, Bottom of Stack, Top of Stack
Previous/Next Unit 
- Show Previous, Show Next
Next Turn 
Here's the image from Matrix CS forums. Please note the icons are not final, there's still a  couple of them Mike's been further tweaking for additional clarity:
![[Image: ToolbarNoneClassicStandardLarge2.jpg]](http://pikt.org/matrix/cs/graphics/ToolbarNoneClassicStandardLarge2.jpg) 
Hope this helps 
