Try this
*PasteUpMorphXX>>acceptDroppingMorph: morphToDrop event: evt*
    (morphToDrop isKindOf: TextMorphXX) ifFalse: [
        ^morphToDrop rejectDropMorphEvent: evt].
    super acceptDroppingMorph: aPiece event: evt.

Best,
Karl


On Mon, Jun 15, 2020 at 3:47 PM Trygve Reenskaug <trygver at ifi.uio.no> wrote:

> Not quite. Joe now throws the the strange Morph back to where it came from
> instead of ignoring it.
> I need Joe to accept all TexMorphXX but ignore the rest.
>
> *PasteUpMorphXX>>acceptDroppingMorph: morphToDrop event: evt*
>     (morphToDrop isKindOf: TextMorphXX) ifFalse: [
>         ^morphToDrop rejectDropMorphEvent: evt].
>
>
>
>
> On 2020.06.15 15:13, karl ramberg wrote:
>
> Hi,
> When you open a morph for dropping it will accept all dropped morphs:
> joe dropEnabled: true.
>
> To filter what is accepted you must override acceptDroppingMorph: aMorph
> event: evt
> Look at implementors for that method.
>
> Best,
> Karl
>
>
>
> On Mon, Jun 15, 2020 at 2:44 PM Trygve Reenskaug <trygver at ifi.uio.no>
> wrote:
>
>> Hi Squeakers,
>> My SRE context browser is a tool for drawing a snapshot of a selected
>> structure of interlinked objects where each object is shown as a
>> rectangular symbol. This diagram shows an object with its class and
>> superclass objects:
>>
>>
>> SRE has worked for years, last in 'Squeak3.10.2'. In 'Squeak5.3', the
>> same program went into an infinite loop. It transpired that *myClass>>processEvent:
>> anEvent using: defaultDispatcher* had become a new thing called an event
>> filter and needed to return an Event or a Symbol. That problem fixed; the
>> program still misbehaves. The problem seems to be with event handling. I
>> have never been into that corner of Smalltalk but have read some Squeak
>> documentation. I have not found any concrete code.  I realize that I will
>> never understand Squeak's event handling by reading code, code comments,
>> and even the documentation I have found. There has apparently been a
>> significant increase in complexity lately. An example: In 3,10,2, class *MorphicEventDispatcher
>> *has 4 methods. In 5,3, it has 16.
>>
>> Here's the beginning of my challenges with 5.3: I find two anomalies in a
>> diagram with just one symbol:
>>
>>    1.     When I move some other window to a position within the
>>    diagram, the diagram grabs it and makes it a submorph of itself.  In
>>    3.10.2, the diagram ignores it.
>>    2.     The cursor becomes a text cursor when I move the mouse across
>>    a symbol.
>>
>> I have no explanation for either anomaly. My SRE code is a kludge and is
>> almost unreadable. It is hard to formulate a question without the whole
>> code as a background, and I have tried to reproduce them in a simple
>> example. I managed to reproduce the first, but not the second anomaly. In a
>> workspace, copy, select,  and do it. The XXX-symbol becomes attached to the
>> cursor, and I place it in the blue background.
>>
>> joe := PasteUpMorph new color: Color lightBlue.
>> joe bounds: (500 at 400 corner: 800 at 600).
>> joe dropEnabled: true.
>> joe openInWorld.
>> circle := CircleMorph new.
>> joe addMorphCentered: circle.
>> tex := TextMorphXX new
>>         contents: 'XXX';
>>         borderWidth: 1;
>>         color: Color red;
>>         extent: 100 at 100.
>> tex openInHand.
>>
>> There is only one  method in class TextMorphXX (sco TextMorph):
>>
>> processEvent: anEvent using: defaultDispatcher
>>     ^#rejected
>>
>>
>>
>> I move some background window,  actually a collapsed Monticello thing, to
>> Joe's position, Joe grabs it and makes it into a submorph. Any hints about
>> how to proceed will be greatly appreciated.
>> --Trygve
>>
>>
>>
>>
>>
>>
>> --
>>
>> *The essence of object orientation is that objects collaborate  to
>> achieve a goal. *
>> Trygve Reenskaug      mailto: trygver at ifi.uio.no <%20trygver at ifi.uio.no>
>> Morgedalsvn. 5A       http://folk.uio.no/trygver/
>> N-0378 Oslo             http://fullOO.info
>> Norway                     Tel: (+47) 468 58 625
>>
>>
>
> --
>
> *The essence of object orientation is that objects collaborate  to achieve
> a goal. *
> Trygve Reenskaug      mailto: trygver at ifi.uio.no <%20trygver at ifi.uio.no>
> Morgedalsvn. 5A       http://folk.uio.no/trygver/
> N-0378 Oslo             http://fullOO.info
> Norway                     Tel: (+47) 468 58 625
>
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