Problem:    Not enough testing for restricted mode and function calls.
Solution:   Add more tests. (Yegappan Lakshmanan, closes #5847)

Problem:    Vim9: crash if return type is invalid. (Yegappan Lakshmanan)
Solution:   Always return some type, not NULL.

Problem:    Various functions not properly tested.
Solution:   Add more tests, especially for failures. (Yegappan Lakshmanan,
            closes #5843)

Problem:    Terminal scroll tests fails on some systems.
Solution:   Remove the fixed 100msec wait for Win32.  Add a loop to wait until
            scrolling has finished. (James McCoy, closes #5842)

Problem:    Listener with undo of deleting all lines not tested.
Solution:   Add a test.

Problem:    Png and xpm files not in MS-Windows zip file.
Solution:   Move files to shared between Unix and Windows target.

Problem:    Swap file test fails on some systems.
Solution:   Preserve the swap file. Send NL terminated keys.

Problem:    Clipboard code is spread out.
Solution:   Move clipboard code to its own file. (Yegappan Lakshmanan,
            closes #5827)

Problem:    Channel contents might be used after being freed.
Solution:   Reset the job channel before freeing the channel.

Problem:    Terminal noblock test is still failing on BSD.
Solution:   Reduce the amount of text.