On Sun, Dec 10, 2017 at 3:26 PM, Markus Seeber <markus.seeber@spectralbird.de> wrote:

You can still statically link for example with FLTK

You still need to ensure that the host can integrate with FLTK (or any other toolkit's) event loop. Without some explicit awareness, events etc. will never be delivered to the non-host toolkit.

and derivatives or roll your
>
own. On Windows I think Steinberg even provides a GUI toolkit for VST plugins if

Not in any effective form. Their old version (more than a decade old) was based on *Motif* for X Window. There's a newer attempt at this, but it no notable benefits unless you wrote the host using the same thing, which is essentially impossible because of it's limited scope.

I remember correctly? Or go plain ImGui or plain OpenGL or whatever suits?

Maybe robin can give better recommendations since he seems to have done some work
on lv2 GUIs. (maybe see https://github.com/x42/robtk )

robtk is probably one of the most obvious answers, but even robin can identify some drawbacks.

the thing is that on other platforms, there's a single event loop that all possible toolkits connect to. on Linux (X Window (and probably Wayland too)), this isn't true. Qt has done work to use the same glib-based event loop as GTK but this isn't a general solution. On Windows or MacOS, it makes no difference what toolkit the host and plugin use, because everything is inevitably going to get routed through the same event loop (and redraw cycle). On Linux this is not true, and it's the root of most of these issues with plugins.