Subject: Re: bug#75936: monitor width reporting

From: "david" <[email-masked]>
Date: Thu, 30 Jan 2025 09:10:41 -0700

> Can you tell more about the differences between these two builds?  Are
> they builds of the same Emacs version with the same configure-time
> switches/options and the same versions of the development tools, or
> are any of those factors different between the builds (and if so,
> which ones)?

> Looks like one of the outputs reports two separate screens, whereas
> the other reports a combined screen?  If so, aren't the differences
> expected?  Or what am I missing?

> The latter Emacs build was configured on a system without XRandr
> headers, XRandr being the X server extension that provides detailed
> monitor information.

The two builds can be run within seconds of each other on the two-screen
setup described; the reported attributes are different; the build
information is the same.  Hence, the attributes information cannot be
relied on by a user.  It looks as though Po Lu has pointed out a difference
at a lower level.  I have created a kludge function that gets it right for
me with 16x9 screens and a sometimes 2x attributes error.

The builds were done six months apart; I have no recollection of the first.
Perversely, the second build was done to check accuracy of my code and
procedures.  The second build was done with a newly downloaded tar file; I
make minor changes to data.c and keymap.c; the patches are available if you
want them: irrelevant, not recommended.  As far as my build procedure is
concerned, I keep it as simple as possible.  For the most part, I involve
only the libraries that are mentioned by configure.  Although, in both
cases, I installed cairo [apt install libcairo-dev] because text size is a
disaster without it.  Cairo is in the build information.  I do not have any
idea how XRandR came into the picture.