Haiku's graphical interface is different from most FLOSS OSes around, as it does not make use of X11, which has consequences on the availability of various known GUI toolkits. Indeed, most of them are quite dependent on X11 features, or sometimes lack features which are already present in X11, leading to applications improperly bypassing the toolkit. Also, since the native toolkit is only available as a C++ API, further concerns arise when porting them over. And the limited number of developers also means some old widespread toolkits aren't yet available while more recent ones already are.

Nevertheless, the advent of proper package management and a port system recently accelerated Haiku's development, leading to many new ports.

We'll detail which toolkits are usable, and what's missing.