patch from colinf that adds an 'empty' preset to the preset drop-down list, so that plugins can be set back to the 'no preset' state rather than being stuck in the state of 'preset loaded and modified'. This should apply to all plugin types, though I've only tried it on LV2 and LADSPA.

git-svn-id: svn://localhost/ardour2/branches/3.0@12787 d708f5d6-7413-0410-9779-e7cbd77b26cf

gtk2_ardour/plugin_ui.cc

@@ -593,6 +593,9 @@ PlugUIBase::preset_selected ()
 			warning << string_compose(_("Plugin preset %1 not found"),
 						  _preset_combo.get_active_text()) << endmsg;
 		}
+	} else {
+		// blank selected = no preset
+		plugin->clear_preset();
 	}
 }
 
@@ -745,6 +748,8 @@ PlugUIBase::update_preset_list ()
 		preset_labels.push_back (i->label);
 	}
 
+	preset_labels.push_back("");
+
 	set_popdown_strings (_preset_combo, preset_labels);
 
 	--_no_load_preset;
@@ -768,6 +773,7 @@ PlugUIBase::update_preset ()
 void
 PlugUIBase::update_preset_modified ()
 {
+
 	if (plugin->last_preset().uri.empty()) {
 		_preset_modified.set_text ("");
 		return;

libs/ardour/ardour/plugin.h

@@ -183,6 +183,7 @@ class Plugin : public PBD::StatefulDestructible, public Latent
 	void remove_preset (std::string);
 
 	virtual bool load_preset (PresetRecord);
+	void clear_preset ();
 
 	const PresetRecord * preset_by_label (const std::string &);
 	const PresetRecord * preset_by_uri (const std::string &);

libs/ardour/plugin.cc

@@ -327,6 +327,16 @@ Plugin::load_preset (PresetRecord r)
 	return true;
 }
 
+void
+Plugin::clear_preset ()
+{
+	_last_preset.uri = "";
+	_last_preset.label = "";
+	_parameter_changed_since_last_preset = false;
+
+	PresetLoaded (); /* EMIT SIGNAL */
+}
+
 /** @param val `plugin' value */
 void
 Plugin::set_parameter (uint32_t which, float val)