For some my macros, I use floating palettes. I set them so that the macro title is not showing, but a custom icon is. It's possible to use app icons, KM icons or emoji etc. The thing is, I often create my own icons (which I apply to buttons on a Stream Deck), and I'd like to be able to apply a custom PNG for a macro icon.
Any image in the Clipboard can be pasted into the selected Icon field of a Macro. And Keyboard Maestro will reduce the image size automatically to 64x64.
So, for a PNG you can open in Preview, ⌘A to select all and ⌘C copy. Then go over to Keyboard Maestro, click the icon field and ⌘V to paste.
Also, once a Macro has an icon, you can select the icon field in the Macro and ⌘C to copy. Then, if you multiple-select as many Macros as you want, ⌘V will paste the same icon on to all of them at once.
Mind blown - I had tried dragging PNGs into the well, tried copying the PNG in finder then pasting, neither worked. Opening in Preview, CMD+A + CMD+C worked!