Let a new window pick its own size instead of forcing a guessed placeholder

Root-caused "windows spawn small and square, not remembering placement or
size": new_managed_window hardcoded a fresh toplevel's geometry to 800x632
before the client had said anything about its own preferred size, and
sync_geometry forced that guess onto the client's very first
xdg_toplevel::configure unconditionally. Per xdg-shell, size: None on that
first configure is how every mainstream compositor lets a client pick its
own natural size instead; this one never did, so every app converged on
the same placeholder rectangle regardless of what it would have chosen.

Window::size_is_provisional marks a size that really was just the guess
(not a remembered geometry, a rule's explicit geometry action, or a
maximize/phone-mode fill, none of which are guesses). sync_geometry sends
size: None for such a window's first configure; a new adopt_provisional_size,
called from the commit handler, adopts the client's own real first size
into Window::geometry the moment it commits one, clamping only position so
a bigger-than-guessed window can't hang off its monitor's edge.

Live-verified in a nested compositor: a zenity dialog now renders at its
own compact natural size instead of being stretched to the old guess.

1 files changed, 9 insertions, 0 deletions

diff --git a/crates/wayland/src/state/lifecycle.rs b/crates/wayland/src/state/lifecycle.rs
index 1749a3c..1afa738 100644
--- a/crates/wayland/src/state/lifecycle.rs
+++ b/crates/wayland/src/state/lifecycle.rs
@@ -10,6 +10,15 @@ impl CompState {
             w.app_id = with_toplevel_app_id(toplevel.wl_surface()).unwrap_or_default();
             w.geometry = srdwm_core::Rect::new(0, 0, 800, 600 + TITLEBAR_HEIGHT as i32 as u32);
             wm.add_window(w);
+            // See `Window::size_is_provisional`'s own doc comment: only
+            // when `add_window` actually used the guessed `800x600` above
+            // (not a remembered size, a rule's own `geometry` action, or a
+            // maximize/phone-mode fill) does the client get to pick its own
+            // size instead - `sync_geometry`/`adopt_provisional_size` are
+            // what actually act on membership here.
+            if wm.window(id).is_some_and(|w| w.size_is_provisional) {
+                self.provisional_size.insert(id);
+            }
             // Starts the open-slide tween (see `WindowAnim`'s doc comment):
             // the window's first `sync_geometry` call below will see this,
             // register the tween, and place it here - a few pixels below