[Lazarus] strange bug in source editor, disappearing scroll bar

[Bernd Kreuss]

please compare these two screen shots:

http://imagebin.org/121695
http://imagebin.org/121699

Pay attention to the scrollbar and the sunken border around the edit
area. All I did was pressing enter on this line. If I remove the line
break again it will reappear, as often as I want. It does not happen
when I move it to a new edit window. It will happen again if I restart
lazarus. It happens only on windows.

I suddenly found this strange behavior *only* on this particular file
today after I made some changes (in a different place!). The scrollbar
re-appeared after switching line numbers off and on again but only until
I tried to scroll, it flickered half a second and the disappeared again.

It was *pure* coincidence that I found this one line that seems to
trigger it because it was initially broken after the Result:= and I
wanted to break it after the then. Then I noticed that it would trigger
this strange bug (or make it go away if it is on one line).

Tomorrow I will do some more experiments, maybe I can make it reliably
reproducible so I have some more substance for a bug report. If needed I
can share the original file that triggers the bug, the project is open
source.

Bernd.