renderer mailbox, focus message

src/renderer/message.zig

@@ -0,0 +1,11 @@
+const std = @import("std");
+const assert = std.debug.assert;
+const Allocator = std.mem.Allocator;
+
+/// The messages that can be sent to a renderer thread.
+pub const Message = union(enum) {
+    /// A change in state in the window focus that this renderer is
+    /// rendering within. This is only sent when a change is detected so
+    /// the renderer is expected to handle all of these.
+    focus: bool,
+};