Spectrum GUI: use horizontal spacer to pack elements on the left

sdrgui/gui/glspectrumgui.ui

@@ -311,6 +311,19 @@
        </property>
       </widget>
      </item>
+     <item>
+      <spacer name="horizontalSpacer_2">
+       <property name="orientation">
+        <enum>Qt::Horizontal</enum>
+       </property>
+       <property name="sizeHint" stdset="0">
+        <size>
+         <width>40</width>
+         <height>20</height>
+        </size>
+       </property>
+      </spacer>
+     </item>
     </layout>
    </item>
    <item row="2" column="0" colspan="3">
@@ -615,6 +628,19 @@
        </item>
       </widget>
      </item>
+     <item>
+      <spacer name="horizontalSpacer">
+       <property name="orientation">
+        <enum>Qt::Horizontal</enum>
+       </property>
+       <property name="sizeHint" stdset="0">
+        <size>
+         <width>40</width>
+         <height>20</height>
+        </size>
+       </property>
+      </spacer>
+     </item>
     </layout>
    </item>
   </layout>