Copy this text to the clipboard, then in Decker you should be able to Edit → Paste Card:
%%CRD0{"c":{"name":"home","widgets":{"highlighter1":{"type":"contraption","size":[128,128],"pos":[224,112],"def":"highlighter","widgets":{"storage":{"image":"%%IMG3AEAAQAKEj6kW7Q/dmrTOiDO0vOsPdqICBlc5il+6plTmLnCMYPRr0/mNb7HPs+w8wCCnKEQak4+jcsmUVJ7QaKN3rf6ap6x2K01Qv07vYVwzjcxlNjeqChPD6LN8em/b2dg43wpQx/AGyCJBiPfXZ3iFuOintnaY1xU5Z3kpOKhYCeb4eOlJ2SnJiTUqg5pqWqkq5kqCWcoaS1Zoq6WJOyu7y6Pr29YbLEq8BGy8+pmcScusDPsciyytkTiso9q0vOksfB3oGvFbty0+1Gy6Ud4CPQ7eLVyCch2pOU8PlxYdjq+rxK3eO0Z/qNniZjAXwoTHAvbjp9DhQ29QBn4zZlEetooS3W0kx3BGFXSiIJ4yKbDjHpJG5rViOdIfPowyrbkoAA=="}}},"sendnum":{"type":"button","size":[96,16],"pos":[112,112],"script":"on click do\n highlighter1.highlighted:5\nend","text":"Send Number"},"happy":{"type":"button","size":[96,16],"pos":[112,144],"script":"on click do\nhighlighter1.highlighted:image[\"%%IMG3AEAAQAKEj6kW7Q/dmrTOiDO0vOsPdqICBlc5il+6plTmLnCMYPRr0/mNb7HPs+w8wCCnKEQak4+jcsmUVJ7QaKN3rf6ap6x2K01Qv07vYVwzjcxlNjeqChPD6LN8em/b2dg43wpQx/AGyCJBiPfXZ3iFuOintnaY1xU5Z3kpOKhYCeb4eOlJ2SnJiTUqg5pqWqkq5kqCWcoaS1Zoq6WJOyu7y6Pr29YbLEq8BGy8+pmcScusDPsciyytkTiso9q0vOksfB3oGvFbty0+1Gy6Ud4CPQ7eLVyCch2pOU8PlxYdjq+rxK3eO0Z/qNniZjAXwoTHAvbjp9DhQ29QBn4zZlEetooS3W0kx3BGFXSiIJ4yKbDjHpJG5rViOdIfPowyrbkoAA==\"]\nend","text":"Send Happy"},"sad":{"type":"button","size":[96,16],"pos":[112,176],"script":"on click do\nhighlighter1.highlighted:image[\"%%IMG3AEAAQAKEj6kW7Q/dmrTOiDO0vOsPdqICBlc5il+6plTmLnCMYPRr0/mNb7HPs+w8wCCnKEQak4+jcsmUVJ7QaKN3rf6ap6x2K01Qv07vYVwzjcxlNjeqChPD6LN8em/b2dg43wpQx/AGyCJBiPfXZ3iFuOintnaY1xU5Z3kpOKhYCeb4eOlJ2SnJiTUqg5pqWqkq5kqCWcoaS1Zoq6WJOyu7y6Pr29YbLAqlYfzJO/MboVOSnEn7+twsKr1XnTYUPbwKvQl8LNwdm51o8g1+jZ0eOEkLPA3b1N5+Tu7+bhrvTf72zc/bKXatkHFC9CTgiYHyBBLL9ychvlyoFFYZY+4hwXsTyWTs1/FiOHtLPnIMeUPhNpEWlxkkeQrWuHVW4rWgGAKkSZbUnj3smTNFAQ==\"]\nend","text":"Send Sad"}}},"d":{"highlighter":{"name":"highlighter","size":[128,128],"margin":[0,0,0,0],"description":"Draws attention to an image","script":"on get_highlighted do storage.copy[] end\non set_highlighted val do\n show[\"called set_image with\" val]\n if \"image\" = typeof val\n storage.clear[]\n storage.paste[val]\n else\n alert[\"%J is not an image\" format val]\n end\nend","image":"%%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","widgets":{"storage":{"type":"canvas","size":[64,64],"pos":[32,32],"locked":1,"border":0,"scale":1}}}}}
There’s a contraption with an embedded canvas, that draws a border around the image on the canvas to highlight it. The contraption has a .highlighted attribute which allows the canvas image to be set or retrieved. There’s also three buttons, one which sets the .highlighted attribute to a number (which should be rejected) and two which set it to an image (to demonstrate the image is actually being changed).
It’s basically the same as my last example, but I had to change the attribute name from .image to .highlighted. It turns out that contraptions already have a .image property (which refers to the background image of the contraption, like card.image refers to the background image of a card), so you can’t override that with your own set_image{} handler. I wrote my original example based on my experience of attributes in general, but I hadn’t actually tested it as written, sorry.