The change table editor is used to modify what columns appear in change
lists with a series of checkboxes. These checkboxes have a click area
that is slightly larger than the checkbox itself in order to make them
easier to click on. This is accomplished by intercepting a click on the
container and relaying it to the checkbox it contains.
However, because one event handler was used for three different
purposes, every time a user clicked on the checkbox container this would
result in two calls to the handler. If the column was being added, this
would mean that it would appear in the preference list twice.
Duplicating preference names is avoided by splitting the event handlers
so that each handler does one thing only. Updates to the preference list
are made my querying the state of the checkboxes rather than making
incremental updates.
The cursor style of the checkbox is updated too.
Change-Id: Icb8c4b94209c62c7794112f36e89183776c73ea8
605bc571e8