Detect XWayland dialogs via WM_TRANSIENT_FOR, not just native xdg_toplevel parent

Window::is_dialog (close-button-only titlebar, no traffic lights) was
only ever set from a native xdg_toplevel's own parent() - redraw_
decoration_buffer's is_dialog computation called dw.toplevel(), which
is always None for an XWayland-backed DWindow (X11Surface's own
accessor is x11_surface(), a different method), so the .unwrap_or(false)
fallback made every XWayland dialog - a GTK "Save As", an app's own
"About" box, anything setting the ICCCM transient-for hint - always
draw with the full three-button titlebar and traffic-light colours,
even though the feature this was built for explicitly wanted the
opposite. Documented as a known gap at the time; now closed.

redraw_decoration_buffer now also checks X11Surface::is_transient_for()
for an XWayland window. property_notify gained a WmWindowProperty::
TransientFor arm that re-runs redraw_decoration_buffer, for a client
that sets the hint slightly after its own initial map - the same
"read fresh every call" pattern the existing xdg_toplevel::parent()
check already relied on, extended to catch a late X11 property the way
the Wayland equivalent (set_parent, any time) already was.

1 files changed, 8 insertions, 9 deletions

diff --git a/crates/core/src/window.rs b/crates/core/src/window.rs
index b30cf7b..6e40486 100644
--- a/crates/core/src/window.rs
+++ b/crates/core/src/window.rs
@@ -160,15 +160,14 @@ pub struct Window {
     /// Geometry to restore to when un-maximizing.
     pub restore_geometry: Option<Rect>,
     pub decorated: bool,
-    /// Whether this window declared an `xdg_toplevel` parent (`set_parent`)
-    /// - a dialog/utility window belonging to another one, not a normal
-    /// top-level app window. Backend-set (the wayland crate reads the real
-    /// `ToplevelSurface::parent()`, refreshed on every decoration redraw),
-    /// same as `decorated` itself; `core` has no protocol concept of its
-    /// own to derive this from. Only ever `true` for a genuine `xdg_
-    /// toplevel` client that set a parent - an XWayland dialog's own
-    /// `WM_TRANSIENT_FOR` isn't read yet, so this misses those specifically
-    /// (a real, known gap, not an oversight). Requested directly: a
+    /// Whether this window declared itself a dialog/utility window
+    /// belonging to another one, not a normal top-level app window --
+    /// a native `xdg_toplevel`'s own `parent()` (`set_parent`), or an
+    /// XWayland `X11Surface`'s ICCCM `WM_TRANSIENT_FOR` hint
+    /// (`is_transient_for()`). Backend-set (the wayland crate reads
+    /// whichever real accessor applies, refreshed on every decoration
+    /// redraw), same as `decorated` itself; `core` has no protocol
+    /// concept of its own to derive this from. Requested directly: a
     /// dialog's titlebar should show only a close button, no traffic
     /// lights - see `hit_test`'s and `decoration::render_titlebar`'s own
     /// use of this for what actually changes.