It doesn’t even take much to reach the limits of tiny GUI toolkits. Very common things like native file/directory selection dialog (preferably with format/suffix filtering) rule out a whole slew of “tiny GUI toolkits”. You can use a puny GUI and find out halfway that widgets you need just aren’t there or require tremendous customization efforts, or you can use Qt and have the widest selection while conforming to accessibility standards and at the same time not look like crap. The choice is obvious to me (after hard-earned lessons).