Macro widget_refs 

macro_rules! widget_refs {
    ( $structname:ident ; $( $i:ident : $t:ty),* ) => { ... };
    ( ;GET_REFS; $structname:ident ; $( $i:ident : $t:ty ),* ) => { ... };
    ( ;REF_STRUCT; $structname:ident ; $( $i:ident : $t:ty ),* ) => { ... };
    ( ;IMPL_GETTERS; $structname:ident ; $( $i:ident : $t:ty ),* ) => { ... };
}