Macro gstore::update_state

macro_rules! update_state {
    (
        $view:ident[$field:expr] => $variable:ident: $t:ty => $handler:expr
    ) => { ... };
}

This code is unsafe! GTK allows to store data on widgets. This is useful sometimes but since GTK is written in C, setting data to widgets is not safe. This widgets needs more work to address this is or should be implemented differently.