Sudden jumping point in buffer. Probably a bug?

[Stefan-W. Hahn]

Hello,

I'm using emacs as 64 bit compiled on windows 7/64 and linux 64 bit. Since
quite a while I have the problem that, while typing, the cursor (point) is
sometimes suddenly jumping to another position in buffer.

First I thought I have touched the touchpad of my laptop. But this also
happened without touchpad on normal keyboard.

I also thought first it just happens on windows. But I saw it a few times on
linux too.

I'm not sure but perhaps it also happens not just in C++ but also in
Org-mode.

My guess that it has something to do with fontifying (semantic?). With this
I have gone through the commits of emacs and saw that at May 4 2015 there
was a change with save-excursion and a new function save-mark-and excursion;
but I haven't seen a bug in implementation at first sight.

Alas I don't know the version of my (older) emacs which haven't had this 
problem.
(Because of this I now compile the git commit signature into the flags like:

./configure --with-x ...  CFLAGS="-g3 -O3" GIT_VERSION="$(git describe)"

With this I have tha signature available in system-configuration-options.)

I even don't have a clue how to produce this. So for the moment I'm doing
ghost bug hunting... :-(

Anybody else having this problem?
Any hint how to dig into the problem? (view-lossage does not show any
unusual)


With kind regards,
Stefan


-- 
Stefan-W. Hahn                          It is easy to make things.
                                        It is hard to make things simple.