Flyout workspace cannot receive first BlockChange event

[alexcui03]

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Description

When we change a block in flyout (when autoClose is false), the first change event is not received in listener, while the later change events are received correctly.

I add a logging breakpoint in devtools at Blockly.Workspace.fireChangeListener, it print out the change event correctly, but the listener isn't called.

Reproduction steps

1. Run Blockly advanced playground, with the following configuration:

• options > toolbox: simple (I use simple toolbox since it won't auto close and it is visible at first, then i can change the block in the flyout, e.g. inputs)
• actions > logging > log flyout events: true

2. Change any fields or inputs.
3. Check devtool, BlockChange event is not printed.
4. Do step 2 again.
5. This time we can see BlockChange in devtool.

Priority

No response

Stack trace

Screenshots

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Browsers

Chrome desktop

[SimonShiki]

This issue's reproduction gif:

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Seems a listener function changed listeners array while dispatching, and make the remain progress get wrong listener.

Here's the result:

[alexcui03]

A simple fix is that we can rewrite FlyoutBase.reflow as below:

  /**
   * Reflow flyout contents.
   */
  reflow() {
    this.reflowInternal_();
  }

The codes to remove and re-add event can be deleted if we believe that reflowInternal_ won't fire BlockChange and BlockFieldIntermediateChange (since reflowWrapper only listen to these two events now).