RE: cursor-color frame parameter cannot equal background-color

[Drew Adams]

>     Put these sexps in buffer *scratch*:
>
>     1. (setq default-frame-alist '((foreground-color . "Blue")
>                                  (mouse-color . "Red")
>                                  (cursor-color . "Red")))
>
>     2. (modify-frame-parameters (selected-frame)
>                               '(;;(background-color . "Black")
>                                 (cursor-color . "Black")))
>
>     Eval #1. C-x 5 2 to create a new frame. The new frame's cursor color
>     is Red
>
>     Eval #2 (in the new frame). The new frame's cursor is now black - no
>     problem. Delete the new frame.
>
>     Uncomment the background-color in #2.
>
>     Eval #1 again and C-x 5 2 to create a new frame.
>
>     Eval #2 (in the new frame). The new frame's cursor is still red -
>     the spec change had no effect in this regard. This is the main bug.
>
> It is not a bug, it is intentionally coded in x_set_cursor_color.  It
> is trying to avoid making the cursor invisible because of a careless
> choice of colors.

Actually, since I filed that bug, I found a way around it.

However, I still would prefer that there be some way to prevent
x_set_cursor_color or whatever from being so smart in particular contexts.
AFAIK, there is nothing preventing you from setting the foreground and
background colors to be the same. I would prefer the same for the cursor,
foreground, background, and pointer colors. At least let Lisp programs
override this prohibition somehow.