This still needs fixing as part of the ruler tool, but here's an awkward workaround I've used. You can use aura radius as a sort of ruler, temporarily. Suppose you're wondering "is that within 1 km range of this weapon?" Then set the token's aura to 1 km. Don't leave it that way, but at least then you can see whether it reaches some particular point on the map. 'For the DM trying to measure things secretly, you can do the same on your enemy tokens on the GM layer -- or make sure the aura is not visible to your players. To avoid awkwardness of aura-adjusting on the fly, I've also made a series of "invisible" tokens with preset player-invisible auras at various distances. Then I can drag from the character section as a quick temporary ruler. Use aura1 with some short distance (so you can find the token to click and delete it again) and aura 2 as the unit of distance you're measuring.