## Summary
object.align now moves selected ruler guides when aligning to the artboard,
matching Illustrator and the existing Distribute behaviour. Guide-only
selection can run align; the Align panel enables its buttons when only
guides are selected. Guides still stay put when objects are in the selection
and Align To is Selection; key-guide behaviour is unchanged.
## Tests
- engine tests_keyguide: guides_selected_alone_align_to_artboard; updated
selected_guides_align_to_a_clicked_key_object for artboard align
- ui-egui align panel: the_align_buttons_align_guides_selected_alone_to_artboard
Closesstorytold/vectorcraft#3463
Co-authored-by: nrq6993-a11y <nrq6993-a11y@users.noreply.github.com>
Distribute Objects and Distribute Spacing space the selected ruler
guides across the axis (vertical ones for the horizontal options,
horizontal ones for the vertical options) together with the selected
objects, as items with no size. Guides along the axis stay where they
are. Two or more guides selected without objects are enough, and the
Align panel's Distribute buttons are enabled for them. With Align to
Artboard, the outermost items go to the artboard's edges.
A key guide (select.key {guide}) is one of those items. With a spacing,
it stays put and the other items are spaced from it, as from a key
object with no size; a key guide along the axis leaves everything where
it is. The Align panel sends the Distribute Spacing value with both
rows of Distribute buttons while a guide is the key, and enables the
value for it.
A lone object selected with ruler guides can be the key (the Selection
tool's click on it), and Align to the key moves the other selected
guides to its edge or centre: vertical guides to left, centre or right,
horizontal ones to top, centre or bottom. Parallel guides line up on a
key guide. Aligning to the selection or the artboard leaves guides alone.
A click with the Selection tool on a guide selected with objects makes
it the key (select.key {guide}), drawn thicker; a click on it again
cancels it. Align to Key Object is on with one object and a selected
guide and makes the guide the key. object.align lines the objects (or
selected anchors) up on the guide's line and leaves the guide where it
is: a vertical guide sets x only, a horizontal one y. The selection
keeps key_guide beside key, never both; it goes with the guide or the
objects, and follows the guide when earlier guides are deleted.
Distribute Spacing doesn't space from a key guide.
