Recreated the space between display and buttons in simple mode

kcalc.ui

@@ -80,6 +80,22 @@
          </property>
         </widget>
        </item>
+       <item>
+        <spacer name="verticalSpacer">
+         <property name="orientation">
+          <enum>Qt::Vertical</enum>
+         </property>
+         <property name="sizeType">
+          <enum>QSizePolicy::Fixed</enum>
+         </property>
+         <property name="sizeHint" stdset="0">
+          <size>
+           <width>0</width>
+           <height>20</height>
+          </size>
+         </property>
+        </spacer>
+       </item>
        <item>
         <layout class="QVBoxLayout" name="verticalLayout" stretch="0,0">
          <property name="leftMargin">