acme looks like acme; every theme gets acme's button, scroll column and 2px rules

acme takes plan9port's own colours (acme.c iconinit, draw.h): selections
#eeee9e in the body and #9eeeee in the tag, black ink; exec and look sweeps
#aa0000 and #006600, white ink; a #99994c scrollbar under a #ffffea thumb;
black rules; a #8888cc tag/body rule and column button.

Every theme: the grip is acme's button, its tag row's full height, in one
scroll column with the scrollbar (rail_px, 12 at a 17px tagline, scaled,
times GripWidth, a percent, default 150; same x0/x1 to the pixel):
focused clean = solid box; focused dirty = box_dirty filled to a box ring
(acme's modbutton); unfocused clean = a box_border ring round the tag's
ground; unfocused dirty = box_dirty a pixel inside that ring. The grid, which
has no ring, marks dirty with a bold * on box_dirty in the grip's second cell
and fills an unfocused grip halfway to its ring. Regions carry a dirty flag.
Column buttons are the same shape, solid. 2px rules between columns and
stacked panes (inside the tag band's slack), none at the window edge; a 1px
tag/body rule halfway between tag and page.

Theme data: tag_sel_bg, sweep_bg/fg, tag_rule, rule_px, rail_px, box_border,
box_dirty. Chrome: rule_px, tag_rule, rail_px, grip_border, grip_focus_ring;
a comptime guard on Chrome's layout forces a wire bump once v8 ships.
Structural rules are exempt from the focus-indicator rule (docs/effects.md).

Tests: acme widths; stacked rule in the slack at two tagline sizes; every
grip-column pixel is band, button, ring or rule, and the button shares the
scrollbar's x0/x1 (4 metrics x top/bottom x focus x dirty); the four grip
states distinct in every native theme with a non-colour dirty cue in the
grid; wire round-trip of the new fields.

Shared files: src/colors.zig, src/surface.zig, src/body_layer.zig,
src/tagline.zig, src/detached/wire.zig, docs/themes.md, docs/config.md,
docs/effects.md, 21 snapshot goldens (the grip cells only),
test/gui-goldens.txt.

Motion flavours differ by design, and drive notice drops and pane moves

1 files changed, 7 insertions, 1 deletions

diff --git a/src/body_layer.zig b/src/body_layer.zig
index a0195fb8..875f2e36 100644
--- a/src/body_layer.zig
+++ b/src/body_layer.zig
@@ -156,6 +156,7 @@ pub fn paintPointerSelection(
 /// The selection colour of each pointer button's sweep: the select button's
 /// and the look and exec buttons', each tinted toward its own accent.
 pub fn buttonTints(th: *const colors.Theme) [3][3]u8 {
+    if (th.sweep_bg) |own| return own;
     const accent2 = if (std.mem.eql(u8, &th.num, &th.str)) th.comment else th.num;
     return .{
         colors.mix(th.sel_bg, colors.mix(th.sel_bg, th.kw)),
@@ -164,6 +165,11 @@ pub fn buttonTints(th: *const colors.Theme) [3][3]u8 {
     };
 }
 
+/// The ink over each button's sweep.
+pub fn buttonInks(th: *const colors.Theme) [3][3]u8 {
+    return th.sweep_fg orelse @splat(th.sel_fg);
+}
+
 /// A pane's body, painted once. A file body with compact tree-sitter
 /// context rows is painted into its body layer -- more rows than the grid
 /// has, the context rows at the tagline's height -- and the grid's rows are
@@ -312,7 +318,7 @@ pub fn renderBody(p: *Pardes, s: *Surface, arena: std.mem.Allocator, pane: *Pane
         // A select sweep over the tag is the tag's selection, painted there
         // in the tag's own selection colours.
         if (b == pardes.sel_slot and @min(sl.r0, sl.r1) < pane.tag_rows) continue;
-        paintPointerSelection(p, s, pane, r, tx, tw, tag_y, body_y, sl, pane.tag_rows, sel_btn[b], th.sel_fg);
+        paintPointerSelection(p, s, pane, r, tx, tw, tag_y, body_y, sl, pane.tag_rows, sel_btn[b], buttonInks(th)[b]);
     }
     // modal line selection (helix `x`): whole body rows, normal mode only
     if ((pane.body.mode == .normal or modal_hover) and pane.body.msel.active) {