Re: "Final" version of tty child frames

[martin rudalics]

Building complains here as

In file included from ../../src/term.c:30:
../../src/lisp.h: In function ‘Ftty_display_pixel_height’:
../../src/lisp.h:406:24: warning: ‘height’ may be used uninitialized 
[-Wmaybe-uninitialized]
  406 |     XIL ((EMACS_INT) (((EMACS_UINT) (n) << INTTYPEBITS) + Lisp_Int0))
      |                        ^
../../src/term.c:4907:14: note: ‘height’ was declared here
 4907 |   int width, height;
      |              ^~~~~~
../../src/lisp.h: In function ‘Ftty_display_pixel_width’:
../../src/lisp.h:406:24: warning: ‘width’ may be used uninitialized 
[-Wmaybe-uninitialized]
  406 |     XIL ((EMACS_INT) (((EMACS_UINT) (n) << INTTYPEBITS) + Lisp_Int0))
      |                        ^
../../src/term.c:4896:7: note: ‘width’ was declared here
 4896 |   int width, height;
      |       ^~~~~

I cannot test much because I hardly ever use Emacs in a terminal window.
Setting size and position of the child frame work seamlessly.  I can
move the child frame completely out of the parent (but have not tried
what happens when it completely covers the parent) or make it invisible
and visible again.

One thing I noticed is that changing the background color works only
after I changed something like the position or size.  Also I would like
to get rid of those |+- borders.  What would I have to do?

martin