bug#17173: 24.4.50; Emacs partially loses display, and redisplay via `C-l' does not fix it

[Drew Adams <drew.adams@oracle.com>]

Close this bug if you feel like it.  This is only to say that since a
few months ago (?) Emacs redisplay seems to be broken.  I do not have a
recipe, but I would be surprised if no one else sees this at all.

If I create a new frame (e.g. C-x 5 f) that partially obscures an
existing frame, for instance, and the select that partially obscured
frame (e.g., by clicking its title bar), so that it is raised again, the
part of the buffer that was obscured looks wiped out (blank).  And
repeated C-l does not fix this.  My workaround is to thumbify and then
dethumbify the frame.  (Probably iconifying and deiconifying would work
too, but I do not iconify anymore.)

This does not happen systematically - just sometimes.

Again, feel free to close this for its lack of reproducible recipe.
Just wanted to give you a heads-up that redisplay is somewhat broken
now.

In GNU Emacs 24.4.50.1 (i686-pc-mingw32)
 of 2014-03-27 on ODIEONE
Bzr revision: 116884 lekktu@gmail.com-20140327173422-cr942b3hn7xjurks
Windowing system distributor `Microsoft Corp.', version 6.1.7601
Configured using:
 `configure --prefix=/c/Devel/emacs/snapshot/trunk
 --enable-checking=yes,glyphs 'CFLAGS=-O0 -g3'
 LDFLAGS=-Lc:/Devel/emacs/lib 'CPPFLAGS=-DGC_MCHECK=1
 -Ic:/Devel/emacs/include''