bug#12406: 24.2.50; frame parameter `menu-bar-lines' and `menu-bar-mode'

[martin rudalics]

>> Because this way we'd have a consistent interface: The presence of a
>> frame parameter would signal "leave this frame alone".
>
> That's inconsistent with the convention that absence of a frame parameter is
> equivalent to its presence with a nil value.  It is similar to proposing that 
we
> give some  special signification to the absense of a key in an alist, as 
opposed
> to a key with value nil.

You're probably right.

> You are unnecessarily coupling things that do not belong together.  That's a 
bad
> idea.  Whether a given parameter should be affected  by a given function is
> logically unrelated to whether the parameter is currently present for a given
> frame, and is logically unrelated to the parameter's current value for a given
> frame.

Maybe.  I never understood things like `tool-bar-lines-needed'.

martin