r = mui.Get(id$, attr$)
The attributes that you can use with this function depend on the class of the specified MUI object. Have a look at the class reference to see what attributes are supported by the different MUI classes. In order to use an attribute with this function, it needs to have an applicability of "G". Attributes of Area class and Notify class can be used on almost all other classes because the Area and Notify classes act as superclasses for most of the other classes.
DebugPrint(mui.Get("my_listview", "active"))The code above returns the index of the currently active entry in the listview that has the identifier "my_listview" by querying the Listview.Active attribute.