[Greasemonkey] Detecting Greasemonkey Version or extensions

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I have a script that does not run the same in Firefox 1.0 and 1.5.  Is there a way for a script to detect which version of Firefox or Greasemonkey is running?

My script is for a rich text editor.  Many people use the Spellbound Extension with it.  I thought it would be nice to put a button on the toolbar to launch Spellbound.  Is there a way for my script to know whether Spellbound is installed?

thanks!

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