Il 22/08/2014 16:44, Michael Thompson ha scritto:
> The implementation of the OnSelectItem event of TListView doesn't
appear to me to be correct.
> With MultiSelect false, selecting a new Item on the list generates,
as expected, two events: the unselect of the previous Item, and the
select of the new one.
> But they're generated in the reverse order. i.e. first the selection
of the new one, then the unselect of the old one.
Out of curiosity, which widgetset are you using? My memory (haven't
checked this for at least 3 years) says the events were fired in
different sequences between different widgetsets. Mind you, I can't
think of how a change in event order will affect any of the examples
you've given.
This behavior is common at least to GTK2 and Qt. That's why I think it
originates in LCL.
I consider it a bug, because the last event generated doesn't represent
the actual final status of TListView (i.e. an Item selected or no Item
selected), but may represent a previous intermediate condition. Extra
code in application is required to sort out things.
There are many differences between different widgetset TListview
implementation, and a lot of care must be exercised if you want your
application behave the same way in all condition.
e.g.: under Qt a programmatical select of an Item doesn't unselect the
previous one, even if MultiSelect is not active, and a programmatical
unselect of an Item doesn't trigger the OnSelectItem event if ViewStyle
is vsList, but does trigger it if the ViewStyle is vsReport!
Giuliano
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