This will do it to a single track (or is it even a single note column, think default is track.) If you want to add to an entire pattern not sure what the easiest way is. Possibly to create a pattern of 4 lines length and use the Merge option from advanced edit?,. (Am I imagining there was Split/Merge function? Can’t find mentioned on tutorials.renoise.com)
OK Merge is called Join, as mentioned in this thread. Split & Merge Patterns? Strangely there are no words written on it at all on the manual pages, only a screen shot of the context menu where you can see it, so you would never find it through searching even using the correct term.
And there is a Script which expands upon what you can do natively it may be worth looking into…
At the moment there are 3 different functions available:
Insert New Row
Insert New Row In Column
Insert New Row In Pattern
‘Insert New Row’ operates on the current track as kazakore has already mentioned.
‘Insert New Row In Column’ operates on the current note column within the current track.
‘Insert New Row In Pattern’ is obviously the one you’re looking for. This will move all pattern rows down, extend the pattern length (if possible), and also adjust the automations for you. I don’t believe it is mapped to anything by default, so you’ll need to search for ‘insert new row’ in the Keyboard preferences, and then assign your preferred keyboard shortcut to the function.