A pane's last row of text is no resize handle; the grip is, and the GUI's rule

A press on a pane's last row began a seam drag, so the row could not be
clicked or swept like the rest of the text (rsearch dragged the handle out
of the way first). Now no row of text is a handle: in the GUI a press on
the 2 px rule between two panes drags their seam, and anywhere the grip
does, as acme's button moves a window -- dragged up or down its own column
it moves the pane's top, either pane down to its tag alone (acme's
coldragwin), dragged down inside itself too. The hover hint over a last row
is gone; column edges resize as they did. Scripts that dragged a seam drag
a grip instead and match their goldens; six goldens lost the hint or moved a
cursor to the clicked text, re-recorded by name.

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

1 files changed, 8 insertions, 1 deletions

diff --git a/src/gui/gui.zig b/src/gui/gui.zig
index 141a802a..ab281cb6 100644
--- a/src/gui/gui.zig
+++ b/src/gui/gui.zig
@@ -1972,7 +1972,11 @@ fn glyphForCodepoint(g: *const Gui, cp: u32) FaceGlyph {
 }
 
 const CellLayout = struct { w: f32, h: f32, x_off: f32, y_off: f32 };
-const MouseCell = struct { col: u16, row: u16, body_hit: ?pardes.Mouse.BodyHit = null, tag_hit: ?pardes.TagHit = null };
+const MouseCell = struct { col: u16, row: u16, body_hit: ?pardes.Mouse.BodyHit = null, tag_hit: ?pardes.TagHit = null, rule_above: bool = false };
+
+/// How near a row's top edge a press is on the rule drawn there between two
+/// panes: the rule's 2 px and a pixel either side.
+const rule_grab_px: f32 = 3;
 const WindowGeometry = struct {
     window_w: f32,
     window_h: f32,
@@ -3420,6 +3424,7 @@ fn dispatch(g: *Gui, in: *Input, sev: *const c.SDL_Event) void {
                     .row = mc.row,
                     .tag_hit = mc.tag_hit,
                     .body_hit = mc.body_hit,
+                    .rule_above = mc.rule_above,
                     .ctrl = (c.SDL_GetModState() & c.SDL_KMOD_CTRL) != 0,
                 },
             });
@@ -3720,6 +3725,8 @@ fn gridCellAtDimensions(
 ) MouseCell {
     const row: u16 = @intFromFloat(@min(@floor(@max(y, 0) / @max(body_h, 1)), 10_000));
     var point: MouseCell = .{ .col = @intFromFloat(@min(@floor(@max(x, 0) / @max(body_w, 1)), 10_000)), .row = row };
+    // On the rule over this row, which is where two panes meet if they do.
+    point.rule_above = row > 0 and @max(y, 0) - @as(f32, @floatFromInt(row)) * @max(body_h, 1) < rule_grab_px;
     if (core) |p| if (p.presentation.pointerFractional(p.screen_w, p.screen_h, x / @max(body_w, 1), y / @max(body_h, 1))) |mapped| {
         for (p.surface.tagLayers()) |*layer| {
             if (layer.tagHit(mapped.x * body_w, mapped.y * body_h, body_w, body_h, tagline_w, @floatFromInt(p.row_metrics.tagline_h))) |hit| {