I've got two separate problems:
a. I'm trying to add an interaction to the template of a repeater (so that when hovering over a list item the same button appears to the right of that item). Is there a way to do that? (right now the only solution I found was going through all list items and adding the interaction separately for each one)
b. I have a repeater list item with interactions for each line (that I've created as mentioned above). sadly these interactions were saved as screen states rather than states of the repeater list. I basically want to use the same repeater list with the same behavior in another screen. Is there an easy way of copying the interactions of the screen to a new repeater list as screen part? (because right now when I'm converting the repeater list to screen part it doesn't convert the interactions).
Right now, the only way you have to reuse interactions, is through the use of screenparts.
There's no way to copy interactions, and as you mention, when converting a control to a screenpart interactions are not copied. However, you can extract the entire state flow to a screenpart and then customize it from there, which might be useful in this particular case. You can do so by opening the interaction explorer, select the state where your repeater was added, right-click it, and select 'Add as new Screenpart', as shown on the image below.
To have the same interactions available on every item of a repeater, you can create a screenpart with those interactions and put an instance inside the repeater template. However, bear in mind that interactions defined on a screenpart can only perform changes on the screenpart itself, so this might not solve your particular case if you need to perform changes over the screen where the repeater is contained.
Let us know if this helps!
Indigo Studio Team.