You're now viewing the history of 'Petals-SE-XSLT 2.3'. You can move the slider to the right to see previous versions. Dont worry, you can always scroll back.
Drag the yellow bar above to a cell on the left to show the changes made since the last version. You can drag two to show the differences of any two versions. Ctrl+click (or Command+click on OS X) on the cells to clear.