[LV2] plea to plugin UI devs

[Robin Gareus]

While we're at it..

Since there are still new plugins with GTK and QT GUI popping up, and
it's been at least 4 years since we last pointed this out, here's a
friendly reminder:

   **Please avoid big toolkit and be careful with C++**

That being said, keep on hacking.


gtk2 + gtk3 cannot exist in the same memory-space, likewise Qt4 + Qt5.
This means a gtk2 host cannot load plugins with a gtk3 GUI, nor can
you load a Qt4 plugin at the same time as plugin using a Qt5 GUI.

While gtk and Qt allows for nicely portable applications, that is
definitely not true for plugin GUIs. fltk is not trivial either.
There are all sorts of edge-cases: e.g. relocating the library
(dependent paths, modules), static initialization/unloading and ABI
compatibility...

The latter also extends to dependencies direct or indirect. A recent
example is sigc++ gcc4/gcc5 ABI incompatibility (gtkmm uses sigc++).

..and that's just the top of the iceberg.

Unless you know what you're doing, at the time of writing the most
sensible way is to use DPF or JUCE or directly openGL (via pugl). AVTK
may become an option soonish.

Cheers!
robin