Avoid clearing the screen in most situations. NOT_VALID should be
equivalent to CLEAR unless some external force messed up the terminal,
for these situations <c-l> and :mode will still clear the screen.
Also eliminate some obsolete code in screen.c, that dealt with that in
vim drawing window 1 can mess up window 2, but this never happens in
nvim.
But what about slow terminals? There is two common meanings in which
a terminal is said to be "slow":
Most commonly (and in the sense of vim:s nottyfast) it means low
bandwidth for sending bytes from nvim to the terminal. If the screen is
very similar before and after the update_screen(CLEAR) this change
should reduce bandwidth. If the screen is quite different, but there is
no new regions of contiguous whitespace, clearing doesn't reduce
bandwidth significantly. If the new screen contains a lot of whitespace,
it will depend of if vsplits are used or not: as long as there is no
vsplits, ce is used to cheaply clear the rest of the line, so
full-screen clear is not needed to reduce bandwith. However a left
vsplit currently needs to be padded with whitespace all the way to the
separator. It is possible ec (clear N chars) can be used to reduce
bandwidth here if this is a problem. (All of this assumes that one
doesn't set Normal guibg=... on a non-BCE terminal, if you do you are
doomed regardless of this change).
Slow can also mean that drawing pixels on the screen is slow. E-ink
screens is a recent example. Avoiding clearing and redrawing the
unchanged part of the screen will always improve performance in these
cases.
clang scan-build noticed that find_command() may bitmask `eap->flags`.
cmd_can_preview() only uses `ea.cmdidx`, but let's fix the warning...
Found by clang scan-build 5.0
Problem: Using try/catch in timer does not prevent it from being stopped.
Solution: Reset the exception context and use did_emsg instead of
called_emsg.
e723c42836
Problem: Can't use input() in a timer callback. (Cosmin Popescu)
Solution: Reset vgetc_busy and set timer_busy. (Ozaki Kiichi, closesvim/vim#1790,
closesvim/vim#1129)
1e8e14552e
Problem: Cursorline not removed when using 'cursorbind'. (Justin Keyes)
Solution: Store the last cursor line per window. (closesvim/vim#3488)
4a5abbd613
Problem: User doesn't notice file does not exist when swap file does.
Solution: Add a note that the file cannot be found. Make the "still
running" notice stand out.
d6105cb408
Problem: When making backups is disabled and conversion with iconv fails
the written file is truncated. (Luo Chen)
Solution: First try converting the file and write the file only when it did
not fail. (partly by Christian Brabandt)
e6bf655bc4
Problem: There is no easy way to get the global directory, esp. if some
windows have a local directory.
Solution: Make getcwd(-1) return the global directory. (Andy Massimino,
closesvim/vim#2606)
5459129af2
Problem: One character cmdline abbreviation not triggered after '<,'>.
Solution: Skip over the special range. (Christian Brabandt, closesvim/vim#2320)
5e3423d192
Problem: MS-Windows: Filter command with pipe character fails. (Johannes
Riecken)
Solution: Find the pipe character outside of quotes. (Yasuhiro Matsumoto,
closesvim/vim#1743, closesvim/vim#3523)
0664089ecc
Problem: Deleting in a block selection causes problems.
Solution: Check the length of the line before adding bd.textcol and
bd.textlen. (Christian Brabandt, closesvim/vim#2825)
35e802e713
