the Idea Shower A launchpad for new ideas on the web.

I came across a time I needed to open a different element then a standard popup menu when clicking the dropdown selector on a toolbar button. I wanted to open a panel instead. To open a different element and hide the popup you can do something similar to this:

Update: You can do this much more efficiently using XBL Bindings.  I highly recommend reading up on them.

Where I learned it: While working on the Read It Later Firefox Extension