Add note in settings regarding UIs in plugin bridges for macOS

resources/ui/carla_settings.ui

@@ -708,7 +708,7 @@
         </layout>
        </widget>
        <widget class="QWidget" name="page_engine">
-        <layout class="QVBoxLayout" name="verticalLayout_18">
+        <layout class="QVBoxLayout" name="verticalLayout_6">
          <property name="margin">
           <number>2</number>
          </property>
@@ -989,6 +989,13 @@
               </property>
              </widget>
             </item>
+            <item row="6" column="0" colspan="3">
+             <widget class="QLabel" name="label_engine_ui_bridges_mac_note">
+              <property name="text">
+               <string>NOTE: Plugin-bridge UIs cannot be managed by Carla on macOS</string>
+              </property>
+             </widget>
+            </item>
            </layout>
           </widget>
          </item>
@@ -1006,9 +1013,9 @@
           </widget>
          </item>
          <item>
-          <layout class="QHBoxLayout" name="horizontalLayout_8">
+          <layout class="QHBoxLayout" name="horizontalLayout_13">
            <item>
-            <spacer name="horizontalSpacer_10">
+            <spacer name="horizontalSpacer_20">
              <property name="orientation">
               <enum>Qt::Horizontal</enum>
              </property>
@@ -1021,7 +1028,7 @@
             </spacer>
            </item>
            <item>
-            <widget class="QLabel" name="label_13">
+            <widget class="QLabel" name="label_22">
              <property name="maximumSize">
               <size>
                <width>22</width>
@@ -1040,14 +1047,14 @@
             </widget>
            </item>
            <item>
-            <widget class="QLabel" name="label_14">
+            <widget class="QLabel" name="label_23">
              <property name="text">
               <string>Restart the engine to load the new settings</string>
              </property>
             </widget>
            </item>
            <item>
-            <spacer name="horizontalSpacer_13">
+            <spacer name="horizontalSpacer_21">
              <property name="orientation">
               <enum>Qt::Horizontal</enum>
              </property>
@@ -1069,7 +1076,7 @@
            <property name="sizeHint" stdset="0">
             <size>
              <width>20</width>
-             <height>225</height>
+             <height>300</height>
             </size>
            </property>
           </spacer>

source/carla_settings.py

@@ -283,6 +283,9 @@ class CarlaSettingsW(QDialog):
             self.ui.ch_exp_prevent_bad_behaviour.setVisible(False)
             self.ui.lw_page.hideRow(self.TAB_INDEX_WINE)
 
+        if not MACOS:
+            self.ui.label_engine_ui_bridges_mac_note.setVisible(False)
+
         # FIXME, pipes on win32 not working, and mis-behaving on macOS
         if MACOS or WINDOWS:
             self.ui.ch_engine_prefer_ui_bridges.setChecked(False)