One macOS behavior this gets wrong that a lot of other clones do too: press-and-hold on menus and select boxes. With the native widgets, you can invoke a menu

One macOS behavior this gets wrong that a lot of other clones do too: press-and-hold on menus and select boxes. With the native widgets, you can invoke a menu item either by clicking the menu, releasing, and then clicking the item - or by pressing down on the menu, dragging to the item, and releasing. Xel doesn't support the latter at all. Other toolkits do but get some details wrong, like - if you release on an item that opens a submenu, it dismisses the menu (but the same doesn't happen if you click such an item after clicking the menu); - macOS assumes you're using the press style if either the mouse moves a significant amount between pressing down on the menu and releasing, or it stays pressed for a certain interval. So if you press a menu, wait a second, and release, it dismisses the menu.