Two questions about the itemchanged and itemerror events

Question

Within PB6.5.1 and PB9.0：

Question 1: In itemchanged event: return 1 In itemerror event: return 3 At runtime,the sequence of events fired is: itemchanged-->itemerror-->itemchanged-->itemerror Why is each event fired twice？

Question 2： In itemchanged event: return 1 In itemerror event: return 2 At runtime,the focus did not move to the next cell. Why？

Thanks.

Answer 1

Question 1: By returning 3 from itemerror, you have rejected the data, which clears the column and triggers the itemchanged again.

As to philosophically why PowerBuilder is designed to work in this fashion, I suspect they thought it would follow the principal of least surprise i.e. they were anticipating people asking why rejecting the input did not trigger itemchanged.

Question 2: The itemchanged event overrides itemerror. In itemchanged you rejected the input and prevented focus changing; in itemerror you now accept the input, but you have not removed the block on focus changing. You should return 2 from itemchanged, since you can then control whether you allow focus to change from the itemerror event, by returning either 1 or 3.

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In case anyone is reading this question without the powerbuilder help files handy:

return values for itemchanged:

0 (Default) Accept the data value
1 Reject the data value and do not allow focus to change (triggers itemerror)
2 Reject the data value but allow the focus to change (triggers itemerror)

return values for itemerror:

0 (Default) Reject the data value and show an error message box
1 Reject the data value with no message box
2 Accept the data value
3 Reject the data value but allow focus to change