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, 18 insertions, 18 deletions

diff --git a/test/gui-goldens.txt b/test/gui-goldens.txt
index 87134609..4c19dc4f 100644
--- a/test/gui-goldens.txt
+++ b/test/gui-goldens.txt
@@ -1,18 +1,18 @@
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-02-second-document 235cdf75f3ce1d5800dbbdd7dcfde066af50cde01231a35d00c66c4310213a05
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-05-body-selection 39103f3747aae07a12b5151e7e377430b88b96e504670ac2f2d0272197eb827b
-06-tag-focus-selection 6a7f50e292f4ede92df24a817218818b93a01fd15fcf39467cf06c3772077834
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-09-collapsed-focus-tint ae66076fdfb0cab9a906b052df257deee5ba91a6274712d52a76d8a7adc5b415
-10-tagbottom dd8ba0d3ecabf3420d000b0c9591a57278179cbd2a9060f849d283f3881d1847
-11-column-tags 6b1731d1611404597c96ad77f34c2d5cd5a81c1085ec68c6779388e07ce28614
-12-multiline-tag 0ea8f8a83fecef0e9a72d11f56bb7174739109d15074c56165274046bab48e17
-13-image 33986b288f6e2f4b3dc82113c7890980fc10362be471b3d6bf04eb1df7785e6b
-14-theme-ink 3c435c76370d09c9856a7b481a52206f4ab0314729da79eef8b442d25fa210fa
-15-theme-acme-light 3cf7ed81fc85ec91b5d448cab3d943f4724d754215944b4525e44885f73bccea
-16-debug d2fcf18c15c1cbf771c0141b7e7f680185a099bec9102af147bf7951446afb16
-17-terminal 9b46bf9969382991243aafba88977db3bd276bb2d72dd06552b1683d3ee7d90e
-18-mid-transition 11473788385e248cd7e1cc952629b3ad9a55c2068b51bf78d1494f631509e343
+01-boot 39c940960ccd264a0ed2e9dd99a2c352a47ca64c67d42e3313ae344713c712ae
+02-second-document 9a810fe372fa37bc3d338d7f0bd04b5224957cb57ef63952c8fc02d1e72e705a
+03-notice b52ebd3860694d35a43e56d149d180249b2609d4a3fc4374347d8cd3b5ebc05c
+04-context-rows-mid-thumb e7b9f5d6da06143fff79b9f2686c29050556173f97c759a4119a201542f993ef
+05-body-selection 06b7cbcf368bb4371873b26f70286fb2b5ada4293b758fa73458157a248c7aa6
+06-tag-focus-selection a781c95cebb8c47a5c5168e1b7f9747f44a0aad043cc4eec1338bb1f08d0a340
+07-prompt-notice f2a39f0d1136d818e57d693873256f2134d89f10805d4078eaaf16a59bece1ce
+08-wide-glyph-edges ad7439148a7705aac6f5f3de3f6a47f9863dccffeba561c70a77e9b9838c5847
+09-collapsed-focus-tint 807bd7621d54948b84cf2965ef463d3928d050259e8ee2d27472b1d3d378f91e
+10-tagbottom 03086852528d9c8a76f5926a7e7ee371200da617db279f42cbbb6825b5f41fce
+11-column-tags 28ac090425c28515893f184b8c1fd0ba1dc3f05c0385372bb23a0b9e2abd080e
+12-multiline-tag 72be302d73e36e6d51d940300d557e34b081b94ce7ec4e50e3bbd56968ed0d58
+13-image 162e6404d5578d1a8c34a8abd152b91d54588e8ddba540e88d48396560c06f71
+14-theme-ink 42b756fd9f1fba42004ac40983bc6c45445fd7d039a970c11378cac652e00d89
+15-theme-acme-light 5cecfb32915c217c5d39492b8708532bd826a8a55ad6b8bd49d61ed5cee29ab9
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