DM_SETCHECK

The ID of the dialog item that you want to change.

Param2 applies only DI_CHECKBOX and can have one of the following values (listing of FARCHECKEDSTATE):

Flag	Description
BSTATE_UNCHECKED	Off - [ ] or ( )
BSTATE_CHECKED	On - [x] or (*)
BSTATE_3STATE	Set to undefined state - [?] (applies only to the items with DIF_3STATE flag set).
BSTATE_TOGGLE	Toggle the item state. For elements with DIF_3STATE flag set the state will be toggled sequentially between "on", "off", "undefined").

Previous state of the item. For DI_RADIOBUTTON returns the ID of the dialog item in the radio button group that was previously checked. (see DIF_GROUP).