Icon Block: Unable to reset width setting

[Mamaduka]

There are a couple of problems with the Icon block's width setting:

1. The freshly inserted block already has a setting marked as resettable. Default values shouldn't be marked so.
2. If you try to reset it, it changes to 12px, and the setting remains resettable. It's an odd loop caused by the blocks 0 width guard effect and the Width settings reset logic, which changes the value to undefined.

Steps to reproduce

1. Enable block and icon experiments.
2. Insert an icon block.
3. Try resetting the width setting.
4. Action can't be done, and the setting remains resettable.

Screencast

CleanShot.2026-02-17.at.13.12.42.mp4

cc @aaronrobertshaw, @t-hamano, @ryanwelcher

[t-hamano]

Personally, I think it would be better to remove the special effects for blocks, as suggested here. If the user enters zero, I think that should be respected, just like we can set the font size of a block to zero.

[Mamaduka]

I'm also in favor of removing this special case effect. The less we use them in our blocks, the fewer problems we'll have in the future.

[Mustafabharmal]

After trying it out, the special “guard effect” that forces a default of 0 and then breaks the reset logic feels a bit overkill for this case. Since it causes unexpected behavior (resetting to 12px and not actually clearing the value), it might be simpler and more effective to remove that effect entirely rather than trying to patch around it.

This would avoid adding extra complexity and help keep the component behavior more predictable.

[Mamaduka]

@Mustafabharmal, that's the current consensus, but I'm waiting for feedback from others who worked on the block.

[ryanwelcher]

The addition of the guard effect was born out of the need to enforce a default value when there is no means to do so using the block supports system. I agree that it's an odd experience and am happy to remove it. The only thing I'd add is that when the control is reset, the the icon is displayed very large.

That being said, I think it makes more sense to address that at the Block Supports level rather than here. Let's remove it and work towards allowing default /minimum values in a separate PR.

[t-hamano]

The only thing I'd add is that when the control is reset, the the icon is displayed very large.

This probably implies a more fundamental issue, where attributes.style.default is defined, but when we reset it, the value is updated to undefined. This issue seems to be occurring in other block supports as well. This may be an issue that should/can be fixed at the block support level.

cc @aaronrobertshaw @andrewserong

For now, I think it's best to move forward with #75624.