[squeak-dev] Help with UiPushButton>>#on:send:to: in Morphic Designer

Tom Beckmann tomjonabc at gmail.com
Tue Jan 11 07:12:27 UTC 2022

The widgets toolkit to which UiPushButton belongs uses a custom event
mechanism called signals. You can find the place where #on:send:to is
"disabled" here:

This is the package that UiPushButton uses to dispatch messages instead:
https://github.com/hpi-swa/signals I believe the signal you're looking for
should be called #pressed then:


Maybe as a debugging strategy (that I haven't tried myself with this
instance because I already the above suspicion), one way you *probably*
could have found this out yourself would have been by overriding the
mouseDown: method in UiPushButton, put a `self halt` at the top and have it
call `super mouseDown:`. Admittedly, you would likely have wound up with
quite a number of indirections (which may not be entirely clear unless
you're deep in Morphic event lingo) until you would have eventually found
that the events are being delegated to this Event Handler object that calls
methods from the "signals" package.

How would you have known to override mouseDown:? Since UiPushButton is a
Morph, it must still follow the Morphic event dispatching rules. Searching
for "mouse" in the Morph methods should give you a couple that seem
promising, and eventually you'd probably have hit the one that triggers a
halt at the right moment :)

Not sure if this was actually helpful but I often find it quite interesting
what sort of strategies people follow when debugging things, so I thought
I'd give it a try :D

On Tue, Jan 11, 2022 at 4:52 AM David O'Toole <deeteeoh1138 at gmail.com>

> I cannot get UiPushButton>>#on:send:to: working; using on: #click it gives
> no error, but events are never sent. When I substitute an SBButton from
> Sandblocks, it works. Am I using the wrong selector with UiPushButton? Or
> perhaps I am missing something else? I would greatly appreciate any help
> you could offer in troubleshooting.
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