Problem:    Code for modeless selection not sufficiently tested.
Solution:   Add tests.  Move mouse code functionality to a common script file.
            (Yegappan Lakshmanan, closes vim/vim#5821)
https://github.com/vim/vim/commit/515545e11f523d14343b1e588dc0b9bd3d362bc2

Skip termcode tests for now.

Problem:    Some Normal mode commands not fully tested.
Solution:   Add a few more tests. (Yegappan Lakshmanan, closes vim/vim#7073)
https://github.com/vim/vim/commit/d1ad99b65470d3e754f6a0588a6b0dc2214a1eab

Cherry-pick test_registers.vim change from patch 8.2.0644.

Problem:    Various Normal mode commands not fully tested.
Solution:   Add more tests. (Yegappan Lakshmanan, closes vim/vim#7059)
https://github.com/vim/vim/commit/8a9bc95eaec53f4e0c951ff8f2686ae5113a5709

Cherry-pick Test_normal_gdollar_cmd() change from patch 8.2.0540.

Problem:    Mode not updated after CTRL-O CTRL-C in Insert mode.
Solution:   Set redraw_mode and use it. (closes vim/vim#10581)
https://github.com/vim/vim/commit/7a1d32809bb5c1527314000983e75125d79192e0

Problem:    No error if an option is given an invalid value with
            ":let &opt = val".
Solution:   Give the error. (closes vim/vim#9864)
https://github.com/vim/vim/commit/8ccbbeb620dcc73154de29c51100fe815cefe109

Problem:    No tests for clicking in the GUI tabline.
Solution:   Add test functions to generate the events.  Add tests using the
            functions. (Yegappan Lakshmanan, closes vim/vim#9638)
https://github.com/vim/vim/commit/b0ad2d92fd19e673ddbbc66742bae3f71778efde

Problem:    When splitting a window the changelist position moves.
Solution:   Set the changelist index a bit later. (closes vim/vim#10493)
https://github.com/vim/vim/commit/e6f13b473cf2c270e4eab214e09be9825320c11b

Cherry-pick Test_nv_hat_count() change from patch 8.2.1593.

Problem:    Not enough testing for movement commands.
Solution:   Add more tests. (Yegappan Lakshmanan, closes vim/vim#6313)
https://github.com/vim/vim/commit/bdd2c290d3cda69e0046c42f0c651f60bc510a16

Cherry-pick test_functions.vim changes from patch 8.2.0183.
Cherry-pick Test_normal18_z_fold() change from patch 8.2.0540.

Problem:    Search code not sufficiently tested.
Solution:   Add more tests. (Yegappan Lakshmanan, closes vim/vim#5999)
https://github.com/vim/vim/commit/224a5f17c6ec9e98322a4c6792ce4f9bb31a4cce

Cherry-pick test_charsearch.vim change from patch 8.2.0448.
Cherry-pick test_search.vim changes from patch 8.2.0619.

Problem:    FEAT_WINDOWS adds a lot of #ifdefs while it is nearly always
            enabled and only adds 7% to the binary size of the tiny build.
Solution:   Graduate FEAT_WINDOWS.
https://github.com/vim/vim/commit/4033c55eca575777718c0701e26635a0cc47d907