Bring to Front / Send to Back

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Cato99 wrote: For example, I want to bring the no. 3 circle shape to the top layer

If I understand right you want that the circle that is in the slot 3 is visible at the top of all the other 4 circles?

Well, instead of scripting you only need to put the number 3 as number 7

The Multiblend works like a pile of papers the Layer 7 is the one at the top and Layer 1 us the one at the bottom and you need to use then the Opacity to show more than 1 layer

So if you if change the order of the multiblend and put 1 as 7 then it will be shown on top of all others when controlling correctly the Opacity

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Cato99 wrote: Even better if each circle shape can be instructed to go to the top layer, or the bottom layer. I realise I can do many instances of my multiblend, with the different shapes and colours in pre-defined order, and use a switch component to select, but this gets very big and time-consuming, especially if I want to add up to 20 shapes

Sorry that I do not understand this, do you want to make an animation where each of the layer with one of the 5 circles cycle through the first position?

As you say you can have multiple Multiblend with different distribution of the circle in different slots and use switch, but you can also use checkboxes on the Opacity of each layer to activate or deactivate when needed

If you need more than 7 images you can nest together multiple multiblend together so you can use more images