556344 - can't delete "Preferences/Applications" item

Status: RESOLVED DUPLICATE of bug 451260

(Firefox :: Settings UI, defect)

Description

[Rufus Laggren]

User-Agent:       Mozilla/5.0 (X11; U; Linux i686; en-US; rv:1.9.1.8) Gecko/20100204 SUSE/3.5.8-0.1.1 Firefox/3.5.8
Build Identifier: Mozilla/5.0 (X11; U; Linux i686; en-US; rv:1.9.1.8) Gecko/20100204 SUSE/3.5.8-0.1.1 Firefox/3.5.8

After adding an "application" (to handle a particular content type) I cannot delete it w/out editing the rdf file. 

I need to delete it because it prevents handling the file type with a "plugin".

After deleting from the mimeTypes.rdf file, the plug-in will once again open the file properly.

Come on people. This problem has been around for years!

Reproducible: Always

Steps to Reproduce:
1. Menu through to Edit/Preference@tab-Applications
2. Cannot delete any existing items.
3.
Actual Results:  
Cannot open file type because existing helper application that you added to Firefox in error is bad - you want to use plug-in to open file instead. BUT Firefox insists on using "helper application" and does not provide _any_ way to delete it.

Editing the mimeType.rdf file to delete bad application allows Firefox to properly open the file with the plug-in.

Expected Results:  
When a user sets an option through the normal menu interface, they should be able to "unset" it w/out editing config files or re-installing!

Need to be able to edit AND DELETE "applications" that might be added in error.

Problem has existed since 2007 at least.......