Allow sampling Terrain in Edit Terrains mode

[eishiya]

In the Map Editor, it's possible to pick a Terrain to use by right-clicking a tile corner/edge, rather than from the Terrains list. This is very convenient, especially when using a terrain set with a lot of terrains.

I'd like to see a similar capability for the Tileset Editor when editing Terrains, so that one can quickly pick a terrain by clicking an existing label, without having to go through the Terrains list. Right-click is already "taken" since it opens the right-click menu. Perhaps right-click with some modifier would work? It wouldn't be consistent with the map editor, but it would better than nothing.

[UliAbo]

I support this request 100%, it would be very useful, especially in complex terrain tile sets enviroments, like we have: So it would often be helpful to check "backwards", which terrain label has been used. We have so many terrains within one terrain set, that the colors are not enough for distinction. The screenshots shows an easy example, but I'm working on far more complex ones, where I use more colors.