9.1..define custom icon for macro changed..cant drag images anymore..how does one do it?

Hi all

so I tried as usual to drag an image to the macro icon symbol but that seems to have stopped working

reading the 9.1 release notes it says:

  • Added support for copy&paste of Icon Image Well images retaining very compressed size icons.

I assume that's changed the way you define macro icons...this maybe silly but how do you do this? there is no explanation in the release notes ;D