Focus on a closed pane goes to the pane that takes its place, never to the one focused before

Dogfood closed a pane in one column and focus jumped to another column, only because that pane was focused last. Now removePane decides for every route (Del, a ctl del, a command pane's end, a 9P remove, a stillborn scratch replaced): the pane that grew into the rows, or the scratch standing in an emptied column; removeColumn gives it to the pane level with it in the column that takes the width. Closing an unfocused pane leaves focus alone. The per-caller focus lines in Del and replaceStillborn are gone, and so is prevFocus.

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

1 files changed, 2 insertions, 3 deletions

diff --git a/src/builtins.zig b/src/builtins.zig
index 76d7dfb0..ed42dfe3 100644
--- a/src/builtins.zig
+++ b/src/builtins.zig
@@ -790,7 +790,8 @@ pub const Newcol = struct {
 };
 
 /// Close the pane. `Del k` gives its rows to the open pane above it and
-/// `Del j` to the one below, each falling back to the other side.
+/// `Del j` to the one below, each falling back to the other side. Focus on
+/// it goes with its rows.
 pub const Del = struct {
     pub const takes_arg = true;
     pub fn run(c: Ctx) void {
@@ -821,8 +822,6 @@ pub const Del = struct {
             return;
         }
         c.p.removePane(c.id, to) catch |err| return c.p.reportError(c.id, "close", err);
-        // Del k|j is a direction: focus lands where the rows went.
-        if (to) |gainer| c.p.active = gainer;
     }
 };