Change the Close button to the standard Close button.

src/main.ui

@@ -324,7 +324,7 @@
       </item>
      </layout>
     </item>
-    <item row="11" column="0" colspan="4">
+    <item row="10" column="0" colspan="4">
      <layout class="QHBoxLayout" name="buttonslayout">
       <item>
        <widget class="QPushButton" name="translation">
@@ -378,27 +378,15 @@
        </spacer>
       </item>
       <item>
-       <widget class="QPushButton" name="close">
-        <property name="minimumSize">
-         <size>
-          <width>100</width>
-          <height>30</height>
-         </size>
-        </property>
-        <property name="maximumSize">
-         <size>
-          <width>100</width>
-          <height>30</height>
-         </size>
-        </property>
-        <property name="text">
-         <string>Close</string>
+       <widget class="QDialogButtonBox" name="close">
+        <property name="standardButtons">
+         <set>QDialogButtonBox::Close</set>
         </property>
        </widget>
       </item>
      </layout>
     </item>
-    <item row="9" column="0">
+    <item row="8" column="0">
      <spacer name="verticalSpacer1">
       <property name="orientation">
        <enum>Qt::Vertical</enum>
@@ -411,7 +399,7 @@
       </property>
      </spacer>
     </item>
-    <item row="10" column="0">
+    <item row="9" column="0">
      <widget class="Line" name="line">
       <property name="minimumSize">
        <size>
@@ -433,13 +421,13 @@
  <connections>
   <connection>
    <sender>close</sender>
-   <signal>clicked()</signal>
+   <signal>clicked(QAbstractButton*)</signal>
    <receiver>MainWindow</receiver>
    <slot>close()</slot>
    <hints>
     <hint type="sourcelabel">
-     <x>539</x>
-     <y>374</y>
+     <x>500</x>
+     <y>376</y>
     </hint>
     <hint type="destinationlabel">
      <x>299</x>