Problem:    Crash when using win_execute() from a new tab.
Solution:   Set the tp_*win pointers. (Ozaki Kiichi, closes vim/vim#5512)
https://github.com/vim/vim/commit/a44b3eeafa57d4904a3de86b132008b93404f0fd

Problem:    Height of quickfix window not retained with vertical split.
Solution:   Use frame_fixed_height() and frame_fixed_width(). (Hongbo Liu,
            closes vim/vim#4013, closes vim/vim#2998)
https://github.com/vim/vim/commit/9e1e358d376284c3aaf3a9f1e568bca297405f62

closes #3608

Problem:    'winfixwidth' is not always respected by :close.
Solution:   Prefer a frame without 'winfixwidth' or 'winfixheight'. (Jason
            Franklin)
https://github.com/vim/vim/commit/c136af29c0b1939076fbae7d36afd90dce740315

Problem:    Still quite a few old style tests.
Solution:   Convert old to new style tests. (Yegappan Lakshmanan)
            Avoid ringing the bell while running tests.
https://github.com/vim/vim/commit/4a6fcf8047de13c7949ab2f27f7774acaec4ae4d