bgiSetGizmoChecked

Sets the checked state of a checkable gizmo control. Searches gizmoMap for the gizmo ID. Returns 0 if gizmo is not checkable (checkable == false). If checked is non-zero, sets isChecked to true and sends BM_SETCHECK with BST_CHECKED. If checked is zero, sets isChecked to false and sends BM_SETCHECK with BST_UNCHECKED. Returns 1 on success, 0 if gizmo not found or not checkable.

This function controls check state for checkboxes and radio buttons. Only works with checkable controls (checkable field must be true). checked is boolean (non-zero = checked, 0 = unchecked). BM_SETCHECK updates visual checkmark. Use for programmatic state changes, form resets, or loading saved settings. For radio button groups, manually uncheck others when checking one (Windows doesn't auto-manage unless using WS_GROUP).