The STATE3 resource-definition statement defines a three-state check box control. The control is identical to a CHECKBOX, except that it has three states: checked, unchecked, and disabled (grayed).
STATE3 text, id, x, y, width, height [[, style [[, extended-style]]]]
If you do not specify a style, the default style is BS_3STATE | WS_TABSTOP.
For more information on the text, id, x, y, width, height, style, and extended-style parameters, see Common Control Parameters.
AUTOCHECKBOX, CHECKBOX, CONTROL