You can use the mouse for designations in DF.
Yes, but it is incredibly unintuitive and clunky.
Doesn't really matter though, Toady will do what he will do.
Beginning of designation:Rightclick-> enter
End/corner of designation: Rightclick->enter
How is that unintuitive? Toady just needs to let us do that will constructed walls.
How is rightclick->enter intuitive?
There is no feedback, no way to judge distance or precision (especially in unexplored underground tiles where there is often no visual grid for reference), and it requires shuffling of your hands because everything else is keyboard-centric. You have to first hit d, use the keyboard to find the correct spot with numpad/arrows + (>)(<) keys, then move your right hand over to the mouse, then right click, then either move your hand back to the keyboard to hit enter or use your left hand to hit enter. Then repeat, right click again, enter again.
On top of this, the feature is entirely undocumented and only discoverable by trial and error or accident because no other menu uses that system of control.
Really... you think this is intuitive? Why can't I just leftclick and drag to define a square? or leftclick->drag to draw and rightclick->drag for a square. That would be about 1000 times more intuitive than rightclick->enter.
No that is not intuitive, that is the point.
Drag and select interface would a god send. Burrows right now are a monumental pain the ass to build and maintain. 3D Drag select would make this a breeze.
The fact that this feature (right click to move the cursor) is undocumented is another failure, all the UI quirks are hidden, which compounds the already sheer rise of the learning curve.
Now do not take that to mean I don't like hotkeys or don't use them. I actually really like the very intuitive hotkeys that DF uses, for this the keyboard is better. But for things like placing buildings, doing designations, selecting dwarfs, targets, etc the mouse is the perfect tool for the job.
A well designed UI makes the best of tools and options it has available. Mouse wheel scrolling in menus for example, this would make the many sub menus exponentially quicker to use.
Context sensitive tool tips: Why do I have to press k and then move the cursor over to object to look at it? Why not use a tooltip natively on mouse over or click from the main menu. The K sub menu serves no purpose and should be the default mode, with other menus accessible through that.
The DF ui is broken in small but crucial ways. UI design and ergonomics is an art that unfortunately toady does not seem to possess, he makes up for that being a genius in other areas but this limitation has to realized. The UI design and/or code needs to be opened up to someone else with more inclination to fix it. I'm not trying to put down DF but it really has no way to progress without a complete UI overhaul, the complexity and beauty of the game is hidden by the impenetrable (for most people) wall of bad UI design and graphics.
Working on making the core game more complex is pointless if players have no way to use it. It actually makes me sad to see such genius wasted in such a way.