Note: After saving, you may have to bypass your browser's cache to see the changes.

• Firefox / Safari: Hold Shift while clicking Reload, or press either Ctrl-F5 or Ctrl-R (⌘-R on a Mac)
• Google Chrome: Press Ctrl-Shift-R (⌘-Shift-R on a Mac)
• Internet Explorer: Hold Ctrl while clicking Refresh, or press Ctrl-F5
• Opera: Go to Menu → Settings (Opera → Preferences on a Mac) and then to Privacy & security → Clear browsing data → Cached images and files.

/* Any JavaScript here will be loaded for all users on every page load. */
var button = {
        "imageFile": "images/5/56/Button_big.png",  //image to be shown on the button (may be a full URL too), 22x22 pixels
        "speedTip": "big text",    //text shown in a tooltip when hovering the mouse over the button
        "tagOpen": "<big>",        //the text to use to mark the beginning of the block
        "tagClose": "</big>",      //the text to use to mark the end of the block (if any)
        "sampleText": "big text"   //the sample text to place inside the block
};
mwCustomEditButtons.push(button);