In reset, we allocated new rows for all the currently visible
lines. We did **not** however, free the 'old' rows.
Fix by not explicitly allocating new rows, but instead allocating
uninitialized rows when needed, and then explicitly erasing the row.
If there already was a row allocated, it is simply erased. If there
wasn't, the a new line is malloc:ed, and then erased.
Before, we converted each axis event's scroll amount to an integer and
scrolled that many lines.
However, axis events are speed sensitive - very slow scrolling will
result in events with a scroll amount that is < 1.0.
For us, this meant we never scrolled a single line. You could slow
scroll all day if you wanted, and still we would never scroll a single
line.
Fix this by aggregating the scroll amount from axis events until the
scroll amount is > 1.0, and then scroll.
When resizing in alt mode, we never updated the saved 'normal'
cursor. This meant that when we exited alt mode, the cursor would be
positioned where it was in the old pre-resize/reflow grid.
Now, we update the saved cursor in the same way we update visible
cursor. The result is that when we exit the alt screen, the cursor
is restored to the same coordinates it would have been updated to had
the resize been done in the 'normal' screen.
This fixes an issue where an 'underline' cursor wasn't visible on
underlined text - the cursor was rendered first, and then shadowed by
the text underline.
This fixes an issue where we failed to restore the cursor correctly
when exiting from the alternate screen, if the client had sent escapes
to save the cursor position while inside the alternate screen.
This was because we used the *same* storage for saving the cursor
position through escapes, as for saving it when entering the alternate
screen.
Fix by using a custom variable dedicated to normal <--> alt screen
switching.
Update the sixels' 'row' attribute when re-flowing a grid, to ensure
it is rendered at the correct place.
This should work in most cases, but will break when the cell size has
changed (e.g. font size increase/decrease, or a DPI change).
This patch also moves the sixel image list from the terminal struct
into the grid struct. The sixels are per-grid after all.
