message: change download-repo-dialog ui default button is OK button
diff: @@ -108,6 +108,9 @@ min-width: 300px;
  <property name="text">
  <string>choose...</string>
  </property>
  + <property name="default">
  + <bool>false</bool>
  + </property>
  </widget>
  </item>
  </layout>
  @@ -255,6 +258,9 @@ min-width: 300px;
  <property name="text">
  <string>OK</string>
  </property>
  + <property name="default">
  + <bool>true</bool>
  + </property>
  </widget>
  </item>
  <item>
  @@ -262,6 +268,9 @@ min-width: 300px;
  <property name="text">
  <string>Cancel</string>
  </property>
  + <property name="default">
  + <bool>false</bool>
  + </property>
  </widget>
  </item>
  </layout>
  