I found a possible fix that needs review:

https://pharo.fogbugz.com/f/cases/12985/Sometimes-multi-selection-is-lost-on-trees

cheers,
Mart�n



On Sat, Feb 22, 2014 at 5:20 PM, Martin Dias <tinchodias@gmail.com> wrote:
On Sat, Feb 22, 2014 at 5:04 PM, Martin Dias <tinchodias@gmail.com> wrote:
> On Sat, Feb 22, 2014 at 4:53 PM, Benjamin
> <Benjamin.VanRyseghem.Pharo@gmail.com> wrote:
>> On 22 Feb 2014, at 16:40, Martin Dias <tinchodias@gmail.com> wrote:
>>>
>>> Mmmmmmm, now that I test it with a mouse instead of a trackpad, I see
>>> it's almost impossible to do not loose the multiple selection before
>>> starting the drag in a TreeModel.
>>
>> Why?
>> Here it works fine (at least as expected)
>> I
>> -click on the first element,
>> -shift click on the last one,
>> -click and drag
>>
>> and it works
>>
>
> Ohhh! I found how to reproduce it: if you start to drag in the bottom
> item, then it works; but if you start in another one, then
> multi-selection is lost.

Another find:
When multi-selecting using control key (I'm on mac), then drag has to
start in the last selected item, otherwise it's list.