A window whose focus moves to a PDF or picture while the cursor glides goes idle: the glide stops instead of holding frames for ever

glideCursor returned early when no cursor was drawn, so a glide under way
(right-click a PDF from a tag: the cursor sets off for the new pane) was
never stepped again and cursor_glide.moving() kept continuous() true: the
GUI redrew at full rate, every frame, until focus came back to a cursor.
With no cursor drawn the glide is now dropped; the next cursor lands.
A pixel shell's only: the terminal has no cursor glide.

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

1 files changed, 38 insertions, 1 deletions

diff --git a/src/draw.zig b/src/draw.zig
index 0ea0b35e..9fcbb15f 100644
--- a/src/draw.zig
+++ b/src/draw.zig
@@ -225,7 +225,15 @@ fn glideCursor(p: *Pardes, s: *Surface) void {
     s.chrome.cursor_alpha = 1;
     s.chrome.cursor_idle_ms = std.math.maxInt(u32);
     if (!builtins.capabilities.lift) return;
-    const box = focusedCursorBox(p, s) orelse return;
+    const box = focusedCursorBox(p, s) orelse {
+        // No cursor drawn (a PDF or picture took focus, a program hid its
+        // own): a glide under way has nowhere to land, and its springs,
+        // never stepped again, held continuous() and the frames on for
+        // ever. It stops; the next cursor lands where it is.
+        p.cursor_glide = .{};
+        p.cursor_crossing = false;
+        return;
+    };
     const motion = animation.Motion.of(p.settings.motion);
     var snap = if (s.cursor) |cursor| cursor.bar else false;
     var frame: PaneFrame = .{};
@@ -2341,6 +2349,35 @@ test "focus moved to another column glides from where the cursor was drawn" {
     try std.testing.expect(!p.cursor_glide.moving() and !p.cursor_crossing);
 }
 
+test "focus moving to a pane with no cursor while the cursor glides lets the session go idle" {
+    if (!builtins.capabilities.lift) return error.SkipZigTest;
+    const p = try Pardes.init(std.testing.allocator, .{ .cols = 120, .rows = 20 });
+    defer p.deinit();
+    var arena: std.heap.ArenaAllocator = .init(std.testing.allocator);
+    defer arena.deinit();
+    p.settings.motion = .smooth;
+    try twoColumns(p, &arena);
+    p.active = 0;
+    p.advance(3 * std.time.ns_per_s);
+    _ = arena.reset(.retain_capacity);
+    _ = try p.render(arena.allocator());
+    p.active = 1;
+    _ = arena.reset(.retain_capacity);
+    _ = try p.render(arena.allocator());
+    try std.testing.expect(p.cursor_glide.moving());
+    // Mid-glide, the pane focused draws no cursor (as a PDF pane does).
+    p.panes[1].?.body.mode = .tty;
+    p.update(.{ .output = .{ .pane = 1, .bytes = "\x1b[?25l" } });
+    p.advance(3 * std.time.ns_per_s + 20 * std.time.ns_per_ms);
+    _ = arena.reset(.retain_capacity);
+    const hidden = try p.render(arena.allocator());
+    try std.testing.expect(hidden.cursor == null);
+    p.advance(5 * std.time.ns_per_s);
+    _ = arena.reset(.retain_capacity);
+    _ = try p.render(arena.allocator());
+    try std.testing.expect(!p.cursor_glide.moving() and !p.continuous());
+}
+
 test "a pane focus reaches brightens on the same spring the one it leaves dims on, and Motion off snaps" {
     if (!builtins.capabilities.lift) return error.SkipZigTest;
     const p = try Pardes.init(std.testing.allocator, .{ .cols = 80, .rows = 24 });