
So you want to extend the toolbar for your mediawiki editors? I know I do. Here is how I did it:
First copy and paste the code at http://www.appropedia.org/MediaWiki:Common.js
Then edit it to match your site and needs. Here is one snippet, with descriptions, in italics, of each of the lines.
mwCustomEditButtons[mwCustomEditButtons.length EB* = { says to MW, "Hey this is gonna be a toolbar button."
"imageFile": "http://www.appropedia.org/images/c/c8/Button_redirect.png", this is the location of your button image - just upload as normal then find the address by clicking through. "speedTip": "Insert hidden Comment", This is what the tool says when the editor hovers. "tagOpen": "This is the first part of what gets inserted when a user clicks the tool. "tagClose": " -->", This is the last part of what gets inserted when a user clicks the tool. "sampleText": "Comment"}; This is the middle part of what gets inserted when a user clicks the tool without any text highlighted.
Note: If an editor has text highlighted when they click the tool, the tagOpen will go before and the tagClose will go after, and no sampleText will be inserted.
Enjoy.