Conditional validation

cformat switch:  X

This is for use with editable text (E) or checkbox (T) columns; forces an exit for validation immediately after each cell edited, but only if the cell changed during editing. For editable read-only (u) cells, X forces an unconditional exit on entrance into the field (for pre-validation). EXITCODE in either case is typically -48, unless there was another reason to exit the tree besides just the need to validate. XTR'XROW and XTR'XCOL will indicate the cell that previously had the focus; XTR'TARGETROW and XTR'TARGETCOL will indicate the "target" cell (the one that was clicked on, or that will be next in the navigation sequence). XTR'XVALIDATE will be 1 if the former cell needs validation (i.e. changed); 2 if the latter (target) cell needs pre-validation, or 3 if they both need validation. See Editable Tree Controls and (x). Note that prior to build 974, X caused unconditional validation.