Since we already have the StoreVisualX() helper, use it all over the
place instead of setting LastVisualX directly.
This will allow us to add more logic to StoreVisualX() add let this
extra logic apply everywhere automatically.
Remember the cursor location in TextEvent just once - when the original
text event happens, so that when we redo after an undo, the cursor is
placed at the location where the actual redone modification happens (as
the user would expect), not at the location where the cursor was before
the undo (which may be a completely unrelated location and may be far
away).
Fixes#3411
Return false if there is nothing to undo/redo.
This also fixes false "Undid action" and "Redid actions" infobar
messages in the case when no action was actually undone or redone.
Handle the case when the cursor itself hasn't really moved to
another line, but its line number has changed due to insert
or remove of some lines above.
In this case, if the cursor is still at its new trailingws,
we should not reset NewTrailingWsY to -1 but update it to the
new line number.
A scenario exemplifying this issue:
Bind some key, e.g. Alt-r, to such a lua function:
function insertNewlineAbove(bp)
bp.Buf:Insert(buffer.Loc(0, bp.Cursor.Y), "\n")
end
Then in a file containing these lines:
aaa
bbb
ccc
insert a space at the end of bbb line, and then press Alt-r.
bbb and ccc are moved one line down, but also the trailing space
after bbb becomes highlighted, which isn't what we expect.
This commit fixes that.
Added option `hltrailingws` for highlighting trailing whitespaces
at the end of lines. Note that it behaves in a "smart" way.
It doesn't highlight newly added (transient) trailing whitespaces
that naturally occur while typing text. It would be annoying to
see transient highlighting every time we enter a space at the end
of a line while typing.
So a newly added trailing whitespace starts being highlighting
only after the cursor moves to another line. Thus the highlighting
serves its purpose: it draws our attention to annoying sloppy
forgotten trailing whitespaces.
