>In theory: > > VST provides a (cross-platform) library (libvstgui) that is used > to draw pixmap GUIs. The plugin code calls UI functions. > >In practice: > > Many plugins call OS specific drawing functions. > >I'm not sure how automation is handled, but I dont think UI controls are >routed via the host, so I'm guess its done on "trust" and fudged timing.
the plugin is supposed to make a callback to the host
("setParameterAutomated") to tell the host about the change in the
parameter value.
