I've posted a workbook that demonstrates one way of doing this. Basically, I've got a blank view that generates the color legend for the dashboard. In this case, I used a duplicate data source to avoid the global filter changing the color legend.
I'd be happy to answer any questions you might have!
Constant Color Legend.twbx.zip 144.7 KB
Nice work around. Thanks Joshua.
Quick question though. I followed this exact method and it worked well. But it seems that when I use this legend on the dashboard, the "Highlight Selected Items" is automatically enabled and I can't disable it on the dashboard. Any ideas how I can fix this?