This "breaks" any C++ plugins which relied on the `GtkWidget*` type being returned from the `gtk_*_new()` constructors. Those plugins require a cast from `void*` to `GtkWidget*` after this compat wrapper was added. ([see here](http://lists.geany.org/pipermail/users/2017-September/010427.html)).
Not sure if it's worth fixing, but it would be easy to put a cast back to `GtkWidget*` to match the return type of the original functions.