>.controlsource='(iif(condition,alias1.field1,alias2.field2))'
>
>which would be recalculated on each refresh. Note the parentheses around the whole expression, which tell the PEM parser (or whatever the engine may be called) to re-evaluate the expression, instead of evaluating it only once, or binding it permanently.
>
>Though, I think a field like the one above may be read-only or at least unbound. I know this is a regular way to include a calculated field into a grid - use something like this in column's controlsource, but I'm not really too sure whether it is bound or not.

This is not possible. ControlSource of the field could be a variable, property or field only. I did tried once what you suggested with no luck despite what properties I try to set. In grids you also receive error when you try to set up the control source of the control in column. You can show expression in the grid column only by setting ControlSource in the grid column, that is different.