Problem:    MS-Windows: background color wrong in Console.
Solution:   Figure out the default console background color. (Yasuhiro
            Matsumoto, issue #10310)

Problem:    ColorScheme autocommand triggered when colorscheme is not found.
            (Romain Lafourcade)
Solution:   Only trigger ColorScheme when loading the colorscheme succeeds.
            (closes #11024)

Problem:    ":wincmd =" equalizes in two directions.
Solution:   Make ":vertical wincmd =" equalize vertically only and
            ":horizontal wincmd =" equalize horizontally only.

Problem:    mapset() does not restore <Nop> mapping properly.
Solution:   Use an empty string for <Nop>. (closes #11022)

Problem:    The 'cmdheight' zero support causes too much trouble.
Solution:   Revert support for 'cmdheight' being zero.

Problem:    No check if the return value of XChangeGC() is NULL.
Solution:   Only use the return value when it is not NULL. (closes #11020)

Problem:    Return value of list_append_list() not always checked.
Solution:   Check return value and handle failure.

Problem:    Flicker when resetting cmdline_row after updating the screen.
Solution:   Do not update cmdline_row. (issue #11017)

Problem:    Tests are flaky because of using a common file name.
Solution:   Rename files and directories to be more unique.