A focus write makes its pane's column the active one, and layout's active is it

Writing a serial to /focus gave that pane the keyboard but left the active
column where it was, so pane/new under Placement acme went elsewhere, and
/layout's active named the keyboard's column rather than where a new pane
would go. A focus write now sets the active column as the user's click
there would, under either Placement, and /layout's active names the active
column, which pane/new and a look place into.

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

1 files changed, 4 insertions, 1 deletions

diff --git a/src/ninep/ctl.zig b/src/ninep/ctl.zig
index 325fc8c8..98120555 100644
--- a/src/ninep/ctl.zig
+++ b/src/ninep/ctl.zig
@@ -486,9 +486,12 @@ pub fn writeFocus(p: *Pardes, req: Req) Reply {
     const text = std.mem.trim(u8, req.data, " \t\r\n");
     const serial = std.fmt.parseInt(u32, text, 10) catch return tree.failText(req.tag, E.INVAL, tree.e_bad_ctl);
     const id = p.paneBySerial(serial) orelse return tree.failText(req.tag, E.NOENT, e_no_pane);
-    // The keyboard goes to the pane itself, off any header that had it.
+    // The keyboard goes to the pane itself, off any header that had it, and
+    // its column becomes the active one, as the user's click there would
+    // make it: pane/new and a look place there next, whatever Placement.
     tagline.exitHeader(p);
     p.active = id;
+    if (pardes.layout.findPane(p, id)) |at| p.setActiveColumn(at.col);
     return .{ .tag = req.tag, .written = @intCast(req.data.len) };
 }