Programming languages and toolkits are complicated topics. You’ve probably managed to use computers a long time without giving either much thought. But when you switched to Linux, suddenly the issue became relevant. That’s because how well an app integrates with the rest of your desktop often comes down to one question: Was it made in GTK+ or Qt? What Are GTK+ and Qt? GTK+ and Qt are toolkits developers use to structure how an app looks and feels.