Fix: Add hidePluginGui() implementation

Source/Plugin/PluginBridgeProcessor.cpp

@@ -215,6 +215,12 @@ void PluginBridgeProcessor::showPluginGui()
         helper.sendCommand("{\"cmd\":\"show_gui\"}");
 }
 
+void PluginBridgeProcessor::hidePluginGui()
+{
+    if (helper.isHelperRunning())
+        helper.sendCommand("{\"cmd\":\"hide_gui\"}");
+}
+
 juce::Array<juce::File> PluginBridgeProcessor::getInstalledPluginFiles() const
 {
     juce::Array<juce::File> results;