Cell border while dragging, column and row lines while changing their size are white not black with OpenGL enable.
Yep, I see what you mean. Can reproduce (in the 5.1 branch, presumably also in master, but I don't have a build at the moment).
The call to the Win32 InvertRect() in WinSalGraphicsImpl::invert() in vcl/win/gdi/gdiimpl.cxx is fun. As far as I see, it has absolutely not effect at all. At least not for its use case when dragging column/row widths/heights as in this bug. (And when using OpenGL, it presumably can't be right at all to call such a GDI function directly?)
(Ah, but it isn't called when using OpenGL, so at least that's fine.)
Interesting that in the OpenGL case, a black line is (incorrectly) drawn in the column/row header area (but then a white line in the spreadsheet cell grid). I wonder if this is a good hint at what goes wrong.
(In the (correct) non-OpenGL case, nothing is draw in the headers.)
What's especially entertaining here is that what the coe actually wants to do is to draw the line being dragged in "invert" ("xor") mode, but fails to do so both in the non-OpenGL (solid black) and OpenGL (solid white) case...
Tor Lillqvist committed a patch related to this issue.
It has been pushed to "master":
tdf#96257: Silly work-around to produce same result on OpenGL and non-OpenGL
It will be available in 5.2.0.
The patch should be included in the daily builds available at
http://dev-builds.libreoffice.org/daily/ in the next 24-48 hours. More
information about daily builds can be found at:
Affected users are encouraged to test the fix and report feedback.
*** This bug has been marked as a duplicate of bug 96919 ***