[TxMt] line numbers/gutter non-scrolling

[plastichairdoo]

hi all - I noticed that the functionality of the gutter isn't what I expected - namely that when I scroll sideways (to the right) in a document I lose the gutter - i.e. it scrolls across to the left with the rest of the text in the doc window... 

not SOP in most text editors!

anyway - is there a way to restore/enable this functionality? it's pretty basic stuff!

cheers,
bennett