hello Bill
In a datawindow you normaly define a Select that goes "behind it" (hit the 'sql' button). (I think you found that part).
The columns of the select apear in the column list. It's not necesary that they also are visible in the datawindow. For example you could create a datawindow that has 3 columns in its select and then delete the columns in the design. From code you can still access those columns.
Other 'columns' might appear since you have the possibility of inserting 'computed columns'. they are used very often and allow you to create a result, based on other columns and expressions. Menu: 'insert', 'control', 'computed field'. (or using the icon '+/-')
if you use a 'higher' version of pb there should be some tabs saying 'column specification' (the columns of the select) and another one saying 'control list' (the columns and computes, etc. that are present on the design layout of the dw (the 'visible' ones). If you don't see those tabs, then go to the menu 'view', 'layouts' and choose the default layout.
I quote:
--------
// the next 3 items are NOT visible on the DataWindow layout. I believe these are/were checkboxes or conditional.
// Why wouldn't I be able to see these in the DW layout?
-- maybe they have been deleted or they can be below a band or with a far 'x' coordinate. if they are deleted they still can be read from code as long as they are present in the select.
// Is there somewhere else I can look in the Source to see if these items are actually used?
-- since a datawindow can be used anywhere and there can be references to its columns anywhere. You'll have to do a search using the name of the datawindow to find all objects using your datawindow. then, you'll have to check each one of them to see if they use certain columns or not. There's no way PB will give a compiler error for lack of a column. You have to do a search to make sure nothing is using an 'unwanted' column. (there are some tools, but a search on top of your target with right mouse button (from the library painter), normally gives you all ocurences.
sorry for the lousy spelling, I'm dutch-spanish
//Could they just have a property set to not visible or something stupid like that?
-- yes columns have a property 'visible' but you will see the column in design mode, even if its visible attribute is put to '0' (not visible).
Hope it helps. Datawindows are great but
regards,
Miguel L.