Opacity compositing

lib/ui/src/window.rs

@@ -1,6 +1,6 @@
 //! Common window model types.
 
-use crate::scene::UiSize;
+use crate::scene::{Color, UiSize};
 
 #[derive(Clone, Copy, Debug, Eq, Hash, Ord, PartialEq, PartialOrd)]
 pub struct WindowId(u64);
@@ -55,6 +55,7 @@ pub struct WindowSpec {
     pub maximized: bool,
     pub fullscreen: bool,
     pub resizable: bool,
+    pub base_color: Color,
 }
 
 impl WindowSpec {
@@ -72,9 +73,15 @@ impl WindowSpec {
             maximized: false,
             fullscreen: false,
             resizable: true,
+            base_color: Color::rgb(0x08, 0x0C, 0x14),
         }
     }
 
+    pub fn base_color(mut self, color: Color) -> Self {
+        self.base_color = color;
+        self
+    }
+
     pub fn key(mut self, key: impl Into<String>) -> Self {
         self.key = Some(key.into());
         self