Like the documentation says, Reflow Lines/Block breaks lines **at** the long line marker if the line breaking is disabled. The problem is that the long line marker marks characters **after** the given column. This means that Reflow Lines/Block should probably reflow at `eprefs->long_line_column + 1`:
https://github.com/geany/geany/blob/b6fe9f17aeae40ab48e73481e618877e65db464b...