Message boxes not properly hinted for some tiling WMs
Bit of a niche issue, but in some tiling WMs (namely Nimdow) the msgBox boxes doesn't float on top of their main window. This is because they are missing the `_NET_WM_WINDOW_TYPE(ATOM) = _NET_WM_WINDOW_TYPE_DIALOG` X11 hint and instead use the `_NET_WM_WINDOW_TYPE(ATOM) = _NET_WM_WINDOW_TYPE_NORMAL` hint. i3 seems, to handle this better, probably because it sets `WM_TRANSIENT_FOR`. This is probably easily solved by calling [`gtk_window_set_type_hint`](https://developer.gnome.org/gtk3/3.16/GtkWindow.html#gtk-window-set-type-hint).