feat(raygui): get message box example working

examples/gui/message_box.zig

@@ -0,0 +1,55 @@
+//! # raylib-zig [gui] example - message box
+//!
+//! Example originally created with raylib-zig 5.6-dev, last time updated with
+//! raylib-zig 5.6-dev
+//!
+//! Example licensed under an unmodified zlib/libpng license, which is an
+//! OSI-certified, BSD-like license that allows static linking with closed
+//! source software
+//!
+//! Copyright (c) Nikolas Wipper 2025
+
+const std = @import("std");
+const rl = @import("raylib");
+const rg = @import("raygui");
+
+// `rl.getColor` only accepts a `u32`. Performing `@intCast` on the return value
+// of `rg.getStyle` invokes checked undefined behavior from Zig when passed to
+// `rl.getColor`, hence the custom implementation here...
+fn getColor(hex: i32) rl.Color {
+    var color: rl.Color = .black;
+    // zig fmt: off
+    color.r = @intCast((hex >> 24) & 0xFF);
+    color.g = @intCast((hex >> 16) & 0xFF);
+    color.b = @intCast((hex >>  8) & 0xFF);
+    color.a = @intCast((hex >>  0) & 0xFF);
+    // zig fmt: on
+    return color;
+}
+
+pub fn main() !void {
+    rl.initWindow(400, 200, "raygui - controls test suite");
+    defer rl.closeWindow();
+
+    rl.setTargetFPS(60);
+
+    var show_message_box = false;
+
+    const color_int = rg.getStyle(.default, .{ .default = .background_color });
+
+    while (!rl.windowShouldClose()) {
+        rl.beginDrawing();
+        defer rl.endDrawing();
+
+        rl.clearBackground(getColor(color_int));
+
+        if (rg.guiButton(.init(24, 24, 120, 30), "#191#Show Message") > 0) show_message_box = true;
+
+        if (show_message_box) {
+            const result = rg.guiMessageBox(.init(85, 70, 250, 100), "#191#Message Box", "Hi! This is a message", "Nice;Cool");
+
+            if (result >= 0) show_message_box = false;
+        }
+    }
+}
+