Fix interactive-resize border/shadow lag without the OOB risk that sank the first attempt

effective_frame_of now returns the live drag target while a window is
being interactively resized (same change as the reverted first attempt),
but two things make it safe this time instead of reintroducing the
out-of-bounds texture sample that reversion was for:

- Every src crop rect built from a window's frame width in udev/render.rs
  and winit/render.rs (titlebar, top border strip, bottom border strip)
  is now clamped against DecorationSignature's own recorded width/
  border_width - the bitmap's actual last-built size - before reaching
  MemoryRenderBufferRenderElement::from_buffer, which does not itself
  validate src against the real texture size. This is a structural floor
  independent of timing, not a repeat of the previous unsafe approach.
- handle_pointer_position now calls redraw_decoration_buffer once per
  resize motion event (throttled to 60Hz via a new
  CompState::resize_redraw_at), closing the lag at its source instead of
  only catching up on the next real client commit. This also fixes the
  shadow bitmap's identical commit-vs-live-position gap for free, since
  redraw_decoration_buffer rebuilds all three bitmaps together.

Updates the TODO.md entry for this bug with the full before/after.

1 files changed, 14 insertions, 0 deletions

diff --git a/crates/wayland/src/state/mod.rs b/crates/wayland/src/state/mod.rs
index a3e9b1a..0ef4346 100644
--- a/crates/wayland/src/state/mod.rs
+++ b/crates/wayland/src/state/mod.rs
@@ -417,6 +417,20 @@ pub(crate) struct CompState {
     /// own blanket call, which never actually checked whether this
     /// specific window was one of the windows that triggered the tick.
     pub(crate) decoration_signatures: HashMap<WindowId, DecorationSignature>,
+    /// When `handle_pointer_position` last called `redraw_decoration_buffer`
+    /// for the window currently being interactively resized - throttles
+    /// that call to once per `RESIZE_REDRAW_INTERVAL` (see `input::pointer`),
+    /// since a pointer
+    /// can emit motion events far faster than a titlebar's text and border
+    /// bitmaps are worth re-rasterizing. Without this the decoration buffer
+    /// only catches up with `effective_frame_of`'s now-live resize geometry
+    /// (see that function's own doc comment) once the drag ends and the
+    /// blanket `sync()` redraw runs - correct, but visibly laggy borders
+    /// for the whole drag. `None` whenever no resize is in progress; reset
+    /// there rather than left stale, so a *new* resize's first motion event
+    /// always redraws immediately instead of inheriting a stale timestamp
+    /// from a previous drag.
+    pub(crate) resize_redraw_at: Option<std::time::Instant>,
     /// Which titlebar button (if any) the pointer is currently over, on
     /// which window, and *when that hover started* - set from `handle_
     /// pointer_position`'s own `hit_test` result, read by `redraw_