The liblv2-gui library that comes with this software package is written for revision 2 of the LV2 specification and is NOT completely compatible with revisions 3 and later. A plugin UI written using it will only work if it is installed to the same bundle as the plugin it is controlling.

liblv2-gui is a C++ library that you can use to write LV2 plugin GUIs in gtkmm by inheriting from a GUI base class and overriding a small number of functions. See LV2 programming for the complete idiot for a tutorial.