A column can be empty, as acme's can; new panes go where acme's makenewwindow puts them

Newcol makes an empty column; closing a column's last pane leaves it empty with
the keyboard on its tag; Delcol and Joincol alone take a column away; the
session's last pane closing quits. The +New stand-in and replaceStillborn /
stillborn_joiner are gone. Every new pane goes through exec.placeNew, which
follows acme's makenewwindow (active column, empty column whole, blank space,
halving the biggest) or, with Placement pardes, the old rules. ColumnTags is
gone: column tags are always shown. A grip drag shows acme's box cursor.

Co-Authored-By: Claude Opus 5.5 <[email protected]>

1 files changed, 28 insertions, 2 deletions

diff --git a/src/gui/gui.zig b/src/gui/gui.zig
index 84ec1c5c..26e9e24d 100644
--- a/src/gui/gui.zig
+++ b/src/gui/gui.zig
@@ -73,6 +73,24 @@ const p9_arrow_set = [32]u8{
     0x7F, 0xFC, 0x7F, 0xFE, 0x7F, 0xFC, 0x73, 0xF8,
     0x61, 0xF0, 0x60, 0xE0, 0x40, 0x40, 0x00, 0x00,
 };
+/// acme's boxcursor (acme.c:956), while a grip carries a pane or column.
+const p9_box_clr = [32]u8{
+    0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF,
+    0xFF, 0xFF, 0xF8, 0x1F, 0xF8, 0x1F, 0xF8, 0x1F,
+    0xF8, 0x1F, 0xF8, 0x1F, 0xF8, 0x1F, 0xFF, 0xFF,
+    0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF,
+};
+const p9_box_set = [32]u8{
+    0x00, 0x00, 0x7F, 0xFE, 0x7F, 0xFE, 0x7F, 0xFE,
+    0x70, 0x0E, 0x70, 0x0E, 0x70, 0x0E, 0x70, 0x0E,
+    0x70, 0x0E, 0x70, 0x0E, 0x70, 0x0E, 0x70, 0x0E,
+    0x7F, 0xFE, 0x7F, 0xFE, 0x7F, 0xFE, 0x00, 0x00,
+};
+const p9_box_mask = blk: {
+    var m: [32]u8 = undefined;
+    for (&m, p9_box_set, p9_box_clr) |*b, s, cl| b.* = s | cl;
+    break :blk m;
+};
 const p9_arrow_mask = blk: {
     var m: [32]u8 = undefined;
     for (&m, p9_arrow_set, p9_arrow_clr) |*b, s, cl| b.* = s | cl;
@@ -1847,6 +1865,7 @@ const Gui = struct {
     pointer_present: bool = false,
     arrow_cursor: ?*c.SDL_Cursor = null,
     link_cursor: ?*c.SDL_Cursor = null,
+    box_cursor: ?*c.SDL_Cursor = null,
     pointer_shape: pardes.Surface.PointerShape = .arrow,
     pointer_mapped: bool = false,
     pointer_cell: ?MouseCell = null,
@@ -2292,6 +2311,9 @@ fn runNative(init: std.process.Init, opts_in: pardes.Options, attach: ?[]const u
     defer if (arrow_cursor) |cursor| c.SDL_DestroyCursor(cursor);
     const link_cursor = c.SDL_CreateSystemCursor(c.SDL_SYSTEM_CURSOR_POINTER);
     defer if (link_cursor) |cursor| c.SDL_DestroyCursor(cursor);
+    // Its hot spot the middle, as acme's {-7, -7} offset puts it.
+    const box_cursor = c.SDL_CreateCursor(&p9_box_set, &p9_box_mask, 16, 16, 7, 7);
+    defer if (box_cursor) |cursor| c.SDL_DestroyCursor(cursor);
     if (arrow_cursor) |cur| {
         _ = c.SDL_SetCursor(cur);
     } else log.err("SDL_CreateCursor: {s}", .{c.SDL_GetError()});
@@ -2427,6 +2449,7 @@ fn runNative(init: std.process.Init, opts_in: pardes.Options, attach: ?[]const u
         .window = window,
         .arrow_cursor = arrow_cursor,
         .link_cursor = link_cursor,
+        .box_cursor = box_cursor,
         .device = device,
         .swapchain_format = swapchain_format,
         .pipeline = pipeline,
@@ -5270,7 +5293,11 @@ fn renderFrame(
 ) !bool {
     if (surface.pointer_shape != g.pointer_shape) {
         g.pointer_shape = surface.pointer_shape;
-        const cursor = if (g.pointer_shape == .link) g.link_cursor else g.arrow_cursor orelse c.SDL_GetDefaultCursor();
+        const cursor = switch (g.pointer_shape) {
+            .link => g.link_cursor,
+            .box => g.box_cursor orelse g.arrow_cursor,
+            else => g.arrow_cursor orelse c.SDL_GetDefaultCursor(),
+        };
         if (cursor) |value| _ = c.SDL_SetCursor(value);
     }
     g.scene_target_failed = false;
@@ -5810,7 +5837,6 @@ test "the layer cover is the per-cell layer scan, over a core's layouts and rand
     var notices = false;
     for (0..32) |step| {
         core.settings.tag_bottom = step & 1 != 0;
-        core.settings.column_tags = step & 2 != 0;
         if (step & 3 == 0) try std.testing.expect(core.executeBuiltinLine(2, "Collapse"));
         core.leader_on = step & 4 != 0;
         if (step & 8 != 0) {