Create text box to display and edit slider value for Image Stack 🎚

[jwyg]

Current behaviour

The slider can be adjusted to set image transparency between 0 and 255 (using P5 tint function), but these values are not displayed.

Desired behaviour

Ideally there should be a text box which:

• displays the current value so users can see and document the transparency value for the images they export, for example to ensure consistency across images that they are generating;
• enables users to edit the current value which would then update the slider accordingly, again so users can generate multiple images with the same transparency value.