Dear List.

The bug report: https://bugs.freepascal.org/view.php?id=33331

has completely changed the behavious of how TTreeview behave!

The old behaviour (sending OLD current node in OnChanging, sending NEW/SELECTED node in OnChange) is consistent across other components as well.

The bug report is closed so i cannot make an objection to this "fix".

It has created a heck loads of bug in our programs due to this change - can this please be reverted?!?

Kind regards,
Torsten Bonde Christiansen

03.04.2018 11:52, Torsten Bonde Christiansen via Lazarus пишет:

I reopened this bug report. Please comment there.

Thank you Maxim!

-Torsten.

Maxim Ganetsky wrote

I reopened this bug report. Please comment there.

But since other opinions are required we should discuss here - the bug tracker is not the place for discussion. I applied the change leading to this issue would like to hear other opinions. Here's what I wrote in bug tracker:

"I don't see anything wrong in the logics of the new behavior: The OnChanging event is fired before the selected node is changed. It has the node which will become the new selected node as a parameter, and you can do some validation and signal in AllowChange whether the change to the new node will be allowed or not. In the event handler you still have access to the currently selected node as TreeView.Selected. Therefore, there is no need at all to duplicate the currently selected node in the node parameter of the event.

This behavior is now compatible with Delphi (it was not before the fix).

Like any bugfix the new code breaks backward compatibility - sorry for the inconvenience if you have relied on the old behavior.

Which other controls have the OnChanging event? I only found TPageControl/TTabControl but they don't pass the changing tab as a parameter. "

You have to list all LCL incompatibilities in the release notes. For 1.9/1.10 they are located at
http://wiki.freepascal.org/Lazarus_1.10.0_release_notes

Ondrej

I can understand the need for being Delphi compatible, but I'm not a fan of changing a behaviour (which IMHO is not a bug) like this which can potentially affect a lot of places in user code.

Regards,
Torsten.

Torsten Bonde Christiansen wrote

The old behaviour (sending OLD current node in OnChanging, sending NEW/SELECTED node in OnChange) is consistent across other components as well.

Please list those other components.

Juha

Torsten Bonde Christiansen wrote

OnI can understand the need for being Delphi compatible, but I'm not a fan of changing a behaviour (which IMHO is not a bug) like this which can potentially affect a lot of places in user code.

Sometimes when Delphi has a bug it makes sense to give up Delphi compatibility. But here the Delphi behavior is very logical, the old Lazarus behavior simply does not make any sense. It is necessary to know the new node in order to be able decide whether the node change should be performed.

I doubt whether a "lot of places" is affected in your code - it is only the OnChanging event handler where you must replace "Node" by "TreeView.Selected". Of course, it depends on the number of treeviews involved, but I doubt also that every treeview has an OnChanging handler. So, please be realistic.

I apologize for this - my memory played tricks on me as i though tabcontrol/pagecontrol (and the likes) also passed the items....

-Torsten.

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