296432 - valueFromPreferences setter shouldn't throw exception

Status: NEW

(Toolkit :: Preferences, defect)

Description

[Nickolay_Ponomarev]

Exceptions from valueFromPreferences (thrown by pref service calls or by
persistentDescriptor setter) should be handled. I think that in case an
exception has occured, the value on the UI element needs to be reset.

Exceptions may be thrown for example when a pref with that name, but a different
type already exists, or when a bad value is passed to pref with type="file".

To test, enter a string to the textbox in the following prefwindow:

<?xml version="1.0"?>
<?xml-stylesheet href="chrome://global/skin/global.css" type="text/css"?>

<prefwindow xmlns="http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul"
        id="test" title="Options" style="width: 40em;">

  <prefpane id="paneGeneral" label="General">
    <preferences>
      <preference id="test.file" name="test.file" type="int"/>
    </preferences>

    <textbox flex="1" preference="test.file"/>
  </prefpane>

</prefwindow>