From 54c14c2e65fe15b097bef11919d6ec8d9fce411a Mon Sep 17 00:00:00 2001
From: Gabriel Schneider <gbrls@0x4200.cafe>
Date: Mon, 28 Sep 2026 20:11:51 -0300
Subject: An empty column shows its theme's empty_col: white in the acme theme,
 as acme paints it

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
---
 src/colors.zig      |  4 ++++
 src/draw.zig        |  1 +
 src/pardes.zig      | 19 +++++++++++++++++++
 src/themes/acme.zig |  2 ++
 4 files changed, 26 insertions(+)

(limited to 'src')

diff --git a/src/colors.zig b/src/colors.zig
index aeff7b00..401b77f1 100644
--- a/src/colors.zig
+++ b/src/colors.zig
@@ -54,6 +54,8 @@ pub const Theme = struct {
     column_box: ?[3]u8 = null,
     column_box_dim: ?[3]u8 = null,
     border: ?[3]u8 = null,
+    /// What an empty column shows under its tag; the border fill without it.
+    empty_col: ?[3]u8 = null,
     search_bg: ?[3]u8 = null,
     search_fg: ?[3]u8 = null,
     diagnostic_error: ?[3]u8 = null,
@@ -144,6 +146,7 @@ pub const ChromeTheme = struct {
     tag_name_fg: [3]u8,
     tag_active_name_fg: [3]u8,
     border: [3]u8,
+    empty_col: [3]u8,
     search_bg: [3]u8,
     search_fg: [3]u8,
     diagnostic_error: [3]u8,
@@ -167,6 +170,7 @@ pub const ChromeTheme = struct {
             .tag_name_fg = th.tag_name_fg orelse th.tag_fg,
             .tag_active_name_fg = th.tag_active_name_fg orelse (th.tag_name_fg orelse (th.tag_active_fg orelse th.tag_fg)),
             .border = th.border orelse th.scroll_track,
+            .empty_col = th.empty_col orelse (th.border orelse th.scroll_track),
             .search_bg = th.search_bg orelse th.sel_bg,
             .search_fg = th.search_fg orelse th.sel_fg,
             .diagnostic_error = th.diagnostic_error orelse (th.fg orelse th.tag_fg),
diff --git a/src/draw.zig b/src/draw.zig
index b12ab52c..8f2f95f9 100644
--- a/src/draw.zig
+++ b/src/draw.zig
@@ -189,6 +189,7 @@ pub fn render(p: *Pardes, arena: std.mem.Allocator) !*Surface {
     // Separators have their own role; a scrollbar need not frame the page.
     const whole = s.regions[0].rect;
     s.fill(whole.x, whole.y, whole.w, whole.h, .{ .bg = .{ .rgb = chrome.border } });
+    for (0..p.ncol) |c| if (p.col_n[c] == 0) s.fill(p.col_x[c], p.topBarHeight() + p.columnBarHeight(), p.col_w[c], s.rows -| (p.topBarHeight() + p.columnBarHeight()), .{ .bg = .{ .rgb = chrome.empty_col } });
 
     for (&p.panes, 0..) |*slot, id| {
         const pane = slot.* orelse continue;
diff --git a/src/pardes.zig b/src/pardes.zig
index bad512a9..e3f4bb60 100644
--- a/src/pardes.zig
+++ b/src/pardes.zig
@@ -1317,6 +1317,25 @@ test "Placement pardes brings back the old rules, and says so in Config" {
     try std.testing.expectEqual(config.Runtime.Placement.acme, p.settings.placement);
 }
 
+test "an empty column shows its theme's empty_col under its tag: acme's white, else the border" {
+    const p = try Pardes.init(std.testing.allocator, .{ .tty_only = true, .cols = 120, .rows = 20 });
+    defer p.deinit();
+    p.newColumn(0);
+    tagline.exitHeader(p);
+    inline for (.{ "acme", "dark" }) |name| {
+        try std.testing.expect(p.executeBuiltinLine(0, "Theme " ++ name));
+        p.chrome_animation.displayed = colors.ChromeTheme.fromTheme(p.theme());
+        p.sync();
+        var arena: std.heap.ArenaAllocator = .init(std.testing.allocator);
+        defer arena.deinit();
+        const s = try p.render(arena.allocator());
+        const cell = s.at(p.col_x[1] + 3, p.screen_h - 2);
+        const want = p.chromeTheme().empty_col;
+        try std.testing.expectEqual(want, cell.style.bg.rgb);
+        if (std.mem.eql(u8, name, "acme")) try std.testing.expectEqual([3]u8{ 0xff, 0xff, 0xff }, want) else try std.testing.expectEqual(p.chromeTheme().border, want);
+    }
+}
+
 test "dragging a column's only pane to another leaves that column in place, empty" {
     const p = try Pardes.init(std.testing.allocator, .{ .tty_only = true, .cols = 160, .rows = 32 });
     defer p.deinit();
diff --git a/src/themes/acme.zig b/src/themes/acme.zig
index d91e626b..693055d6 100644
--- a/src/themes/acme.zig
+++ b/src/themes/acme.zig
@@ -27,6 +27,8 @@ pub const theme = .{
     .lineno = .{ 0x99, 0x99, 0x80 },
     .scroll_track = .{ 0x99, 0x99, 0x4c },
     .scroll_thumb = .{ 0xff, 0xff, 0xea },
+    // acme paints a column with no window white (cols.c:187).
+    .empty_col = .{ 0xff, 0xff, 0xff },
     .palette = .{
         .{ 0x00, 0x00, 0x00 }, .{ 0xaa, 0x22, 0x22 }, .{ 0x22, 0x80, 0x22 }, .{ 0x88, 0x66, 0x00 },
         .{ 0x22, 0x44, 0xbb }, .{ 0x99, 0x33, 0x99 }, .{ 0x11, 0x88, 0x88 }, .{ 0x55, 0x55, 0x55 },
-- 
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