This toolbar controls some of the view settings for the Valve Hammer Editor.
Toggle Grid, Toggle 3D Grid - These toggle the grid on and off in the 2D and 3D views.
Smaller Grid, Larger Grid - These decrease and increase the grid size. The [ and ] hotkeys can also be used for this purpose.
Load, Save Window State - These buttons are used to save and restore window configurations when the independent window configuration is being used. Independent window usage can be enabled or disabled in the General options.