>> What runtime error did you encounter and what host did you use?
>

> I tried it in Ingen. With your code, when I double click plugin (to show
> GUI) it reports "Failed to instantiate Plugin UI" and Ingen GUI freezes
> (although, engine still runs in background).

That's interesting. Unfortunately, I couldn't get Ingen to compile on
my machine (running Arch), so I cannot test this at the moment. But I
will look out for it and compare with other LV2 GUIs. I actually
copied the code from the example in the GUI header file (forgot its
name, will check at home).
Any chance that this is a bug in Ingen? (It shouldn't crash, but I
know I'm being a little bold to pass on the origin of the crash from
my untested whacky haphazard code to a well-tested program which is
used by many more people...)

> I'm pretty new to templating too and, even though your code made some sense,
> I was comparing it to another very simple example of LV2 GUI code (just a
> button too but without MIDI support), and only difference in code (and in
> crashing Ingen :)) was that line.

Thanks for your input. I hope I can get Ingen compiled and see for
myself where the problem lies.