Fix: [OSX] Fonts loaded directly from a file have to be registered with CoreText for proper text layout.

src/os/macosx/string_osx.cpp

@@ -289,6 +289,17 @@ void MacOSResetScriptCache(FontSize size)
 	_font_cache[size].reset();
 }
 
+/** Register an external font file with the CoreText system. */
+void MacOSRegisterExternalFont(const char *file_path)
+{
+	if (!MacOSVersionIsAtLeast(10, 6, 0)) return;
+
+	CFAutoRelease<CFStringRef> path(CFStringCreateWithCString(kCFAllocatorDefault, file_path, kCFStringEncodingUTF8));
+	CFAutoRelease<CFURLRef> url(CFURLCreateWithFileSystemPath(kCFAllocatorDefault, path.get(), kCFURLPOSIXPathStyle, false));
+
+	CTFontManagerRegisterFontsForURL(url.get(), kCTFontManagerScopeProcess, nullptr);
+}
+
 /** Store current language locale as a CoreFounation locale. */
 void MacOSSetCurrentLocaleName(const char *iso_code)
 {