diff --git a/source/backend/engine/CarlaEngineNative.cpp b/source/backend/engine/CarlaEngineNative.cpp
index 8ac9f610d..fd44a38f7 100644
--- a/source/backend/engine/CarlaEngineNative.cpp
+++ b/source/backend/engine/CarlaEngineNative.cpp
@@ -1509,6 +1509,22 @@ protected:
         else
         {
             fUiServer.stopPipeServer(5000);
+
+            // hide all custom uis
+            for (uint i=0; i < pData->curPluginCount; ++i)
+            {
+                CarlaPlugin* const plugin(pData->plugins[i].plugin);
+
+                if (plugin != nullptr && plugin->isEnabled())
+                {
+                    if (plugin->getHints() & PLUGIN_HAS_CUSTOM_UI)
+                    {
+                        try {
+                            plugin->showCustomUI(false);
+                        } CARLA_SAFE_EXCEPTION_CONTINUE("Plugin showCustomUI (hide)");
+                    }
+                }
+            }
         }
     }
 
diff --git a/source/carla_host.py b/source/carla_host.py
index a4a2de2b5..908b28c3a 100644
--- a/source/carla_host.py
+++ b/source/carla_host.py
@@ -1788,13 +1788,13 @@ class HostWindow(QMainWindow):
         QMainWindow.showEvent(self, event)
 
         # set our gui as parent for all plugins UIs
-        if self.fParentOrSelf == self:
+        if not self.host.isPlugin:
             winIdStr = "%x" % self.winId()
             self.host.set_engine_option(ENGINE_OPTION_FRONTEND_WIN_ID, 0, winIdStr)
 
     def hideEvent(self, event):
         # disable parent
-        if self.fParentOrSelf == self:
+        if not self.host.isPlugin:
             self.host.set_engine_option(ENGINE_OPTION_FRONTEND_WIN_ID, 0, "0")
 
         QMainWindow.hideEvent(self, event)