In cursor's Goto(), which is currently only used by undo and redo, we
restore remembered LastVisualX and LastWrappedVisualX values. But if
the window had been resized in the meantime, the LastWrappedVisualX
may not be valid anymore. So it may cause the cursor moving to
unexpected locations.
So for simplicity just reset these values on undo or redo, instead of
using remembered ones.
Restore the original meaning of LastVisualX before commit 6d13710d93
("Implement moving cursor up/down within a wrapped line"): last visual x
location of the cursor in a logical line in the buffer, not in a visual
line on the screen (in other words, taking tabs and wide characters into
account, but not taking softwrap into account). And add a separate
LastWrappedVisualX field, similar to LastVisualX but taking softwrap
into account as well.
This allows tracking last x position at the same time for both cases
when we care about softwrap and when we don't care about it. This can be
useful, for example, for implementing cursor up/down movement actions
that always move by logical lines, not by visual lines, even if softwrap
is enabled (in addition to our default CursorUp and CursorDown actions
that move by visual lines).
Also this fixes a minor bug: in InsertTab(), when `tabstospaces` is
enabled and we insert a tab, the amount of inserted spaces depends on
the visual line wrapping (i.e. on the window width), which is probably
not a good idea.
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.
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.
Modified behavior of CursorUp, CursorDown, CursorPageUp etc:
if softwrap is enabled, cursor moves by visual lines, not logical lines.
TODO: implement it also for Home and End keys: move cursor to the
visual start or end of a line. I haven't implemented it for now, because
I'm not sure what should be the behavior of StartOfTextToggle then
(considering that Home key is bound to StartOfTextToggle by default).
Fixes#1598
These actions reintroduce the behavior of micro where the Home key
toggles between the start of text (first) and the start of the line.
The same applies for the variant with selection. This commit also
sets these bindings as the defaults.
