There appears to be a conflict with the saved tool pallet locations between v5 and v6. I just downloaded WIP 6.15 and opened my empty template file. The top image shows the pallet config for Rhino 5, but 6.15 changes some pallet locations, including Box Edit (bottom image). All of my tools are on my second monitor. I moved the pallets back into position and save the template file with a v6 name. When I went back to v5, the pallets were displace again so I moved them back. But opening v6 they had moved again and I had to reposition them a third time going back to v5. You may want to check the prefs files for all pallet locations including the Box Edit window. Thank you.
