Problem in running two instances of an extension in Firefox

[Ebrahim Khalil Abbasi]

Dear all,

I developed an extension that works as a pattern matching search engine. The search engine takes as input a code fragment and finds in the source code of a page all other code fragments that are structurally matching the given code pattern. The search engine fails when I follow this scenario:

• I open a tab in Firefox, configure the search engine with code fragment A, and launch the search engine. It works fine. 
• I open a new tab with a new URL, configure the search engine with code fragment B, and launch the search engine. The search engine logically works and reports out that it could not find any matching code fragment, but it should find.   When I close the first tab, it finds the matching code fragments and works properly. 

I think the problem is that the search engine triggered in the second tab assumes the code fragment A as the input and not B, that is why when I close the first tab, it works. 

Is this a normal property of Firebug, or the problem comes from my extension? 

Thanks for any help. 

Ebrahim