Great!  And if it is necessary to create a new Event to extend
attributes of an original Event, it could wrap it.  I always felt
Event data should be basically immutable..

On Wed, Jun 15, 2016 at 4:20 AM,  <commits at source.squeak.org> wrote:
> Marcel Taeumel uploaded a new version of Morphic to project The Trunk:
> http://source.squeak.org/trunk/Morphic-mt.1181.mcz
>
> ==================== Summary ====================
>
> Name: Morphic-mt.1181
> Author: mt
> Time: 15 June 2016, 11:20:40.050378 am
> UUID: 855f8338-73de-5947-9dc5-99e912d115a2
> Ancestors: Morphic-mt.1180
>
> ixes regression in event dispatching and coordinate transformations. Do not reset transformation in the event copy delivered to submorphs. They need those for, e.g., double click, drag-and-drop, etc.
>
> Our events do, more or less, not change after being created and initialized. The only exception is #wasHandled, #wasIgnored, and #position during event dispatching. Keep it that way. If you plan to change some event state in an event filter, create a new event instead and do not mess around with the current one.
>
> =============== Diff against Morphic-mt.1180 ===============
>
> Item was changed:
>   ----- Method: MorphicEventDispatcher>>dispatchEvent:toSubmorphsOf: (in category 'private') -----
>   dispatchEvent: anEvent toSubmorphsOf: aMorph
> +       "Dispatch the given event to the submorphs of the given morph. For coordinate transformations, work only with copies. Either return the given event or a copy of any filtered event to employ immutability to some extent. --- PRIVATE!!"
> -       "Dispatch the given event to the submorphs of the given morph. --- PRIVATE!!"
>
> +       | localEvent filteredEvent |
> -       | filteredEvent |
>         aMorph submorphsDo: [:child |
> +               localEvent := anEvent transformedBy: (child transformedFrom: aMorph).
>                 filteredEvent := child
> +                       processEvent: localEvent
> -                       processEvent: (anEvent transformedBy: (child transformedFrom: aMorph))
>                         using: self. "use same dispatcher"
> +               filteredEvent == #rejected ifFalse: [ "some event or #rejected symbol"
> +                       self flag: #overlappingChildren. "mt: We cannot give two overlapping siblings the chance to handle the event!!"
> +                       filteredEvent == localEvent
> +                               ifTrue: [
> +                                       localEvent wasHandled ifTrue: [anEvent copyHandlerState: localEvent].
> +                                       anEvent wasIgnored: localEvent wasIgnored.
> +                                       ^ anEvent]
> +                               ifFalse: [
> +                                       filteredEvent := filteredEvent copy.
> +                                       filteredEvent translateTo: anEvent position. "restore to untransformed coordinates"
> +                                       filteredEvent wasHandled ifFalse: [filteredEvent copyHandlerState: anEvent]. "restore handler if needed"
> +                                       ^ filteredEvent]]].
> -               filteredEvent == #rejected ifFalse: [ "filteredEvent or #rejected"
> -                       filteredEvent translateTo: anEvent position. "restore to untransformed coordinates"
> -                       filteredEvent wasHandled ifFalse: [filteredEvent copyHandlerState: anEvent]. "restore handler if needed"
> -                       self flag: #overlappingChildren. "mt: We cannot give two overlapping siblings the chance to handle the event!!"
> -                       ^ filteredEvent]].
>
>         ^ #rejected!
>
>