Hello.

I am trying to create a parameter that will function as a parent to another parameter using DESC_PARENT_COLLAPSE. with the code below.

```
cid = DescLevel(idAngleEdgeThreshold, DTYPE_REAL, 0);
if (!singleid || cid.IsPartOf(*singleid, NULL))
{
BaseContainer bc;
bc = GetCustomDataTypeDefault(DTYPE_REAL);
bc.SetInt32(DESC_CUSTOMGUI, CUSTOMGUI_REALSLIDER);
bc.SetInt32(DESC_UNIT, DESC_UNIT_DEGREE);
bc.SetFloat(DESC_STEP, PI / 180.0);
bc.SetFloat(DESC_MIN, 0);
bc.SetFloat(DESC_MAX, PI);
bc.SetFloat(DESC_DEFAULT, 0);
bc.SetInt32(DESC_PARENT_COLLAPSE, -1);
bc.SetString(DESC_NAME, "Angle Threshold"_s);
if (!description->SetParameter(cid, bc, DescMainTabGroup))
return TRUE;
}
cid = DescLevel(idAngleEdgeInvert, DTYPE_BOOL, 0);
if (!singleid || cid.IsPartOf(*singleid, NULL))
{
BaseContainer bc;
bc = GetCustomDataTypeDefault(DTYPE_BOOL);
bc.SetInt32(DESC_PARENT_COLLAPSE, idAngleEdgeThreshold);
bc.SetInt32(DESC_CUSTOMGUI, CUSTOMGUI_BOOL);
bc.SetString(DESC_NAME, "Invert"_s);
bc.SetBool(DESC_DEFAULT, FALSE);
if (!description->SetParameter(cid, bc, DescMainTabGroup))
return TRUE;
}
```

This code works properly to set the parameter as a parent of the other.

My question is it possible for me to control whether the twirl down will be open or closed based on the user selecting different parameters or pressing something like a button?

I looked at the sdk and in the Description Settings Manual it is specifically stated that the child parameter is hidden until the user click on the little arrow, is it possible to control this or is this functionality only available to a user.

Any help would be greatly appreciated.

John Terenece