don't over-expand built-in file dialog on very long paths/names

Change-Id: Ia8167833b54bcfc68f1a306e58a1134a38d64ef6
Reviewed-on: https://gerrit.libreoffice.org/18843Reviewed-by: Caolán McNamara <caolanm@redhat.com>
Tested-by: Caolán McNamara <caolanm@redhat.com>

fpicker/uiconfig/ui/explorerfiledialog.ui

@@ -59,6 +59,7 @@
                         <property name="visible">True</property>
                         <property name="can_focus">True</property>
                         <property name="hexpand">True</property>
+                        <property name="max_width_chars">40</property>
                       </object>
                       <packing>
                         <property name="expand">False</property>
@@ -279,6 +280,7 @@
                                 <property name="visible">True</property>
                                 <property name="can_focus">False</property>
                                 <property name="hexpand">True</property>
+                                <property name="max_width_chars">40</property>
                               </object>
                               <packing>
                                 <property name="left_attach">1</property>