there are a few ways to do this, but i`ll go through the way i use, and im sure people who use other methods will chime in
after you`ve placed all your buttons on the homescreen, hit file>import and import your image you want as a focus highlight.
how copy and paste that image as many times as you need.
hint> if you have 6 icons in a row you can use one an a seperate layer then move the layer on each icon focus in the svg
when you have you image where you need them, in the objects panel on the right, right click on the image and click `convert to animation`. repeat this process for all the highlights (if placing on same layer as buttons make sure is behind the icon)
now what i do is rename the animations, this just makes it a touch easier, so for example focus_1 to focus_6
now click on the button you wish to have the focus behind, and in the inspector panel click the `focus in` line.
in the popup box you`ll see what looks like an open eye (show), click that and you`ll see it makes a new line in the space below, this will reflect either a button or animation which can be changed by selecting from the dropdown box below (this is where having them named logically helps) and on the right of the line you`ll see when the action happens, such as focusin. if your in the wrong state then just click the `focus in` radio button on the top.
so now it should say somethings like `show focus_1 on focusin`
now hit the closed eye icon (to the right of the open one - this is hide) and now change the item in the drop down box so its the same as above, then in the radio button section make sure you choose `focusout` and what your left with in the panel below is something like
launch application on activate
show focus_1 on focusin
hide focus_1 on focusout
repeat these steps for each highlight you wish to make.
i`ll be honest its alot easier than it sounds, and when youve done one or two it`ll literally take you seconds to do each one