This happens in an operation which both increases topline and also
inserts new lines somewhere in the remaining are. So before drawing any
line, win_update() is performing two grid_scroll operations.
===
A
B
C
D
E^
F
===
Consider that new line will be inserted after line E and screen also
scrolled up to line C. First the topline will be adjusted (x is the
scrolling region, ! invalid/empty space created by the scroll):
===
C x
D x
E^ x
F x
! x
! x
===
and then space is inserted for the new line
===
C
D
E^
! x
F x
! x
===
The problem is that we are now assuming that any invalid area ! created
by a scroll is filled with actual contents (by win_line etc) before it
is scrolled again. But in this case the last invalid line ! gets
scrolled. Ideally we should make win_update smarter and just scroll
valid lines for the later scroll (it is just wasteful to scroll the
larger area anyway), but for the 0.4 releasejust make
the compositor ignore such an invalid line (as it will get overdrawn
anyway later).
add proper msg_set_pos event, delet win_scroll_over_*
make compositor click through unfocusable grids
add MsgArea attribute for the message/cmdline area, and add docs and tests
The screen resize logic needs to be refactored to be simpler and more
deterministic. Until then, we need to handle attempts to draw outside of the
screen size gracefully, just like the old vim code did.
fixes#9989
The interaction between 'winblend' and doublewidth chars in the background
does not look very good. But check no chars get incorrectly placed
at least.
Also check that hidden EndOfBuffer region (from style="minimal") blends
correctly.
Why?
- Because we can.
- Because the TUI is just another GUI™
- Because it looks kinda nice, and provides useful context like 1 out of 100
times
Complies with "don't pay for what you don't use".
Some crashes for resizing were unfolded, add tests for those.
Initially we will use this for the popupmenu, floating windows will
follow soon
NB: writedelay + compositor is weird, we need more flexible
redraw introspection.
