Use intrinsic (buffer) size when geometry is not set

The simplest clients like vkcube do not set geometry, and were left
without decorations

src/deco.rs

@@ -21,6 +21,7 @@ use crate::{buffer::SimpleBufferPool, globals::Globals, util::Bounds};
 
 #[derive(Default, Debug, Clone, PartialEq)]
 struct DecoParams {
+    has_geometry: bool,
     bounds: Bounds,
 }
 
@@ -156,6 +157,23 @@ impl Deco {
         deco
     }
 
+    pub fn handle_intrinsic_size(&self, width: i32, height: i32) {
+        let mut params = self.next_params.borrow_mut();
+        if params.has_geometry {
+            return;
+        }
+        log::debug!(
+            "decoration {:?} handling buffer size {width}x{height}",
+            self.wl_surface
+        );
+        params.bounds = Bounds {
+            x: 0,
+            y: 0,
+            width,
+            height,
+        };
+    }
+
     pub fn handle_window_geometry(
         &self,
         x: i32,
@@ -167,7 +185,9 @@ impl Deco {
             "decoration {:?} handling geometry {width}x{height} @ {x},{y}",
             self.wl_surface
         );
-        self.next_params.borrow_mut().bounds = Bounds {
+        let mut params = self.next_params.borrow_mut();
+        params.has_geometry = true;
+        params.bounds = Bounds {
             x,
             y,
             width,