Added file path recommendation in help doc

Author: georgweiss

app/display/editor/doc/widgets_properties.rst

@@ -26,4 +26,14 @@ is ``$(pv_name)\n$(pv_value)``. In case a PV is not defined by the user for such
 anything useful. In such cases user should consider to change the tool tip property value, or set it to an empty value.
 
 An empty tool tip property will suppress rendering of a widget tool tip, even if the value for the tool tip text is
-set by a rule.
+set by a rule.
+
+File Property
+-------------
+
+Some widget use a File property to identify a resource, local or remote. If such a reference is a local file, then
+user is advised to use relative a path as an absolute
+path may not be portable between hosts, in particular not between Windows and Linux/Mac hosts.
+
+File paths may be specified using both forward slash (/) or backslash (\\) as path separator as both will work interchangeably
+between Windows and Linux/Mac.