header-line and mode-line buttons have no mouse-face or hot-zone pointer

[Drew Adams]

Buttons in the header-line and mode-line do not have the appearance of hot
zones.

1. They have no mouse-face.

The code of Buffer-menu-make-sort-button seems to indicate that the
mouse-face for the header line should be highlight. Maybe I'm reading this
wrong, but shouldn't a mouseover on the header line show the highlight
face - it does nothing. Is this a bug?

Similarly, the current mode is a button in the mode-line, but there is no
mouse-face indicating this on mouseover.

2. They have no hot-zone pointer

The mouse pointer for active links is a pointing finger. There is no special
mouse pointer for active buttons in the header-line and mode-line. Is this a
bug?

In Info, for instance, mouseover the header-line buttons: the pointer does
not change to indicate the hot zone. Yet the header-line buttons are
underlined as if they were links, so it appears to the user as if some links
have one pointer and some have another. A similar problem appears in Buffer
List (though there the buttons are not even underlined).

In Customize, the pointer changes to the finger pointer over buttons, so
there is no problem there. The only problem appears to be in the header-line
and mode-line.

Users will count on the pointer to tell them when they are over a hot zone.
In the case of buttons (at least in the header-line and mode line) there is
no such indication.