Fix a few things with chain/effect parameters as reported by Gale

src/BatchCommands.cpp

@@ -349,7 +349,16 @@ wxString BatchCommands::PromptForPresetFor(const wxString & command, const wxStr
       return wxEmptyString;   // effect not found.
    }
 
-   return EffectManager::Get().GetPreset(ID, params, parent);
+   wxString preset = EffectManager::Get().GetPreset(ID, params, parent);
+
+   // Preset will be empty if the user cancelled the dialog, so return the original
+   // parameter value.
+   if (preset.IsEmpty())
+   {
+      return params;
+   }
+
+   return preset;
 }
 
 double BatchCommands::GetEndTime()

src/PluginManager.cpp

@@ -2289,7 +2289,19 @@ wxFileConfig *PluginManager::GetSettings()
 
 bool PluginManager::HasGroup(const wxString & group)
 {
-   return GetSettings()->HasGroup(group);
+   wxFileConfig *settings = GetSettings();
+
+   bool res = settings->HasGroup(group);
+   if (res)
+   {
+      // The group exists, but empty groups aren't considered valid
+      wxString oldPath = settings->GetPath();
+      settings->SetPath(group);
+      res = settings->GetNumberOfEntries() || settings->GetNumberOfGroups();
+      settings->SetPath(oldPath);
+   }
+
+   return res;
 }
 
 bool PluginManager::GetSubgroups(const wxString & group, wxArrayString & subgroups)

src/effects/EffectManager.cpp

@@ -168,6 +168,13 @@ wxString EffectManager::GetEffectParameters(const PluginID & ID)
 
       effect->GetAutomationParameters(parms);
 
+      // Some effects don't have automatable parameters and will not return
+      // anything, so try to get the active preset (current or factory).
+      if (parms.IsEmpty())
+      {
+         parms = GetDefaultPreset(ID);
+      }
+
       return parms;
    }