Yes, you're right (of course). It didn't work for me the first time, but that's because I pasted in a value like "#4caf50". It works if I just paste "4caf50" (without the hex symbol). I expected that it would take the same string that I copied from the designer property slot.
Also, it didn't update when I pasted and pressed Enter. I had to click the Copy button or tab to another field. But that's a REALLY tiny quibble.