Hi Keith,

a) It seems that there is some fuzziness in the way Entity Selections and 
Collections are understood. Let's try to make it more precise:

- An Entity selection doesn't 'contain' the Entities, it's a List of Entity 
References (in this case, a reference is a 4D internal référence on the Record 
which is referenced by the Entity)

- A Collection has to fit in memory, for each element is a memory object 
contained (if scalar) or referenced (if not scalar) by the corresponding 
Collection Element.

During the WT2019, I've demonstrated (1st day), and explained (2nd day) that 
you can mix these notions into Collections of entity references (for instance).

b) The best way to Highlight elements in a ListBox is LISTBOX SELECT 
ROW(*;"listBox";0;lk add to selection)! If it crashes 4D when the listbox 
contains a large number of lines, it's a bug.

c) If the listbox contains a large number of lines, I wonder why it would be 
necessary to highlight all, for highlighting is just for UI...(But this is just 
a remark ;-)

Anyway, from the feedback I got from the East part of the WT in US, it seems 
that you may find an interest to come to one of the next events, and get some 
more information about how it works, and why it works like this, and how to 
choose the best technique without playing Blind Man's Bluff with ORDA. We are 
here (the Team and myself) to share all the experience we acquired by exploring 
and opening up the different paths. 

Anyway, the first day is for free, you will see many technical demos, and a 
glance on the future, on the evolution of 4D and what's coming next, you will 
get a lot of demos and source code, and also lunch and coffee!

And if you find it interesting enough,if you think that you still have 
something useful to learn, if you feel that you are not yet at the top of your 
capabilities, you can then register for the second day, where we dive deeply 
into the code and techniques. We will try to answer your questions, we will do 
our best to illuminate the road of men who have become lost in their code, and 
(like it did for most of the previous attendees), it will save you a precious 
and valuable time when you'll be back home.

I hope to meet you in Austin, Seattle, or San José!

My very best,


> On 16 Apr 2019, at 17:49, 4d_tech-requ...@lists.4d.com wrote:
> I'm looking for a fast way to highlight a selection of rows in an entity 
> selection listbox.  The way I am aware of works OK unless the listbox gets a 
> large number of rows.
> Adding records to the Selected Items name in the Property list does not 
> highlight the listbox contents.  The equivalent of adding records to the 
> "UserSet" is not available with entity selection listboxes.
> Highlighting all with LISTBOX SELECT ROW(*;"listBox";0;lk add to selection) 
> crashes 4D if the listbox contains enough records.
> LISTBOX SELECT ROW(*;"listBox";$position;lk add to selection) crashes if put 
> in a fast FOR loop.  If the loop is executed more slowly there is success.  
> The slowness comes from looking for entitySelected[i] within the entity 
> selection and highlighting its position in the listbox.
> Is there a better way to get there?

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