darwin: temporarily set window background to be transparent. examples: Add core-transparent-window and remove input from core-triangle

examples/core-transparent-window/main.zig

@@ -0,0 +1,22 @@
+const std = @import("std");
+const mach = @import("mach");
+
+// The set of Mach modules our application may use.
+const Modules = mach.Modules(.{
+    mach.Core,
+    @import("App.zig"),
+});
+
+// TODO: move this to a mach "entrypoint" zig module which handles nuances like WASM requires.
+pub fn main() !void {
+    const allocator = std.heap.c_allocator;
+
+    // The set of Mach modules our application may use.
+    var mods: Modules = undefined;
+    try mods.init(allocator);
+    // TODO: enable mods.deinit(allocator); for allocator leak detection
+    // defer mods.deinit(allocator);
+
+    const app = mods.get(.app);
+    app.run(.main);
+}