tdf#122808 search formatting dialog should be modal

Change-Id: I8b33fcbbf538660703f6cdb9818e8fae2c623be9
Reviewed-on: https://gerrit.libreoffice.org/66674
Tested-by: Jenkins
Reviewed-by: Caolán McNamara <caolanm@redhat.com>
Tested-by: Caolán McNamara <caolanm@redhat.com>

cui/uiconfig/ui/searchformatdialog.ui

@@ -6,6 +6,7 @@
     <property name="can_focus">False</property>
     <property name="border_width">6</property>
     <property name="title" translatable="yes" context="searchformatdialog|SearchFormatDialog">Text Format </property>
+    <property name="modal">True</property>
     <property name="type_hint">dialog</property>
     <child>
       <placeholder/>