On Thu, Jul 26, 2018 at 4:14 PM Eli Zaretskii <eliz@gnu.org> wrote:

which on the current trunk is around line 16920, please insert this
line:

clear_glyph_matrix (w->desired_matrix);

before this line:

if (!try_window (window, startp, 0))

Then try running with this change for a while, and see if it solves
the assertion violations and doesn't produce any unintended adverse
effects.

OK, I have added that line, rebuilt and running it with gdb attached, will keep you posted.

Thanks!