The top-left cell is 0,0. The class constants AllColumns and AllRows can be used to specify that you wish to get or set all the values columns or rows.
Taken from https://documentation.xojo.com/api/user_interface/desktop/desktoplistbox.html.CellTextAt
AllColumns and AllRows throwing a “This items does not exist” ???
Do you prefixed them with their class name, DesktopListBox?
Yes 
Not at my Desk right now, i’m trying to write an example from my mind:
Var strLine As String = Me.CellTextAt( Me.SelectedRowIndex, DesktopListBox.AllColumns)
This issue was reportedly fixed but made it to release without being tested <https://xojo.com/issue/66525> and still seems to be an issue/missing.
Var myContent As String = DesktopListbox.Content
This is not a bug but a change by xojo.
It should be get/set but only get seems to be documented?
I’m not really sure how a dump of the tables content relates to changing all values on a row?
And not the issue i’m talking about here 
as you wish…
In the past i used a simple
String = Listbox.Cell(row, -1)
but now i have to use a For…Next loop, which feels inefficient. 
I have used that often both for setting and getting row data over the years…
They seem to want to diminish listbox functionality in some of ways… It is/was very convenient for a number of situations and helped keep code bloat down.
The API 1 listbox has a LOT little things that they may not see a use for (or don’t want to have to support) going forward, but they were put in originally because they were seen as useful…
Those of us who tamed the beast (learned them all and used all those things) found they were things that helped make Xojo more of a RAD product for us.
-Karen
I hope the DesktopListBox will evolve further. And AllRows/AllColumns show us, that Xojo Inc. also is seeing a need for a “-1” solution.
-1 works in .RefreshCell()
Ah I now see what was changed back in [https://xojo.com/issue/66525 ](https://xojo.com/issue/66525), the sample was removed that showed AllColumns but it was left in the Notes section just above it.
In that case, it looks like this feature has been stealth removed as there was no notes about it on the ticket above and the edit yesterday didn’t fix the error talked about in the OP.
It seems like they’ve taken the enum magic wand to everything as you can’t even use -1 like you used to be able to as you get an out of bounds error now when trying that, maybe they forgot to implement it, only time will tell.