This ensures that the start or end x values do not get adjusted when
they are off the viewport in rectangle select.
This also includes some tests for the toViewport method.
Fixes#1339.
This fixes a couple of subtle rectangle select behaviors:
* Corrects how selection rolls over when crossing the x-boundary; this
was mentioned in #1021, this properly corrects it so both sides of the
x-boundary do not share characters.
* Corrects a minor quirk in the selection of initial cells in a
selection - this can be more readily observed when selecting a single
line with rectangle select. To correct this, we only use the x axis
when calculating this instead of both x and y.
This fixes an issue where selections from the bottom-right to the
top-left (or top-left to bottom-right), in addition to some single-line
rectangle selections, were not working.
This works by handling situations where only one of the x or y
axes in the start or end points may need to be flipped to get the
correct top-left or bottom-right of a selection. We call these kinds of
orientations "mirrored", like you were looking in a mirror.
This also adds a small bit of logic that keeps these kinds of motions in
rectangle selection from selecting the character before or after it.
This has the current side-effect of anchoring a rectangle selection to
the original characters if you change directions during the selection,
something I will look at in a later commit.
Finally, this also removes rectangle select on double-click. I thought
this might be a good idea, but word select in rectangle mode really
does not work (the effect seems pretty erratic), and it's not
implemented in Kitty either.
Fixes#1008.
This adds rectangle select mode; when dragging with ctrl+alt (or
super+alt on MacOS), this allows you to select a rectangular region of
the terminal instead of the full start-end points of the buffer.
