When designating the area to harvest things from, there are some situations in which it refuses to start or finish the area designation process.
First, when selecting for harvesting, if the cursor is pointing at the side of a cliff when you left-click the mouse it will not start the designation process or if you are pointing at the side of a cliff when you release the mouse it will finish the designation process and you’ll need to left-click the mouse again somewhere else.
Secondly, if the cursor is pointing at an informational message (for instance “Click and drag to harvest resources|Right click to exit this mode” or the “Paused” message), it will either block your attempt to start dragging out a shape or fail to complete the shape (in which case you need to left-click the mouse again somewhere else).
It seems like some of these things should not happen.
The informational panels should never block you from dragging out a shape. I realise you can left-click on the “Pause” message to make time return to normal, but if you are in the middle of drawing out a shape, you clearly don’t want to do that. I notice that if you are in “harvest selection” mode, the “Pause” button won’t do anything if you click and drag on it anyway. It will if you do in “floor selection” mode though. Some inconsistency there.
When designating a harvest area, the game should be able to handle you finishing your designation pointing at the side of a cliff. The game already handles the case of you starting your selection on one side of a cliff and ending on the other side (it selects everything under the area, even if you can’t see the whole area). It should do the exact same thing as in that case.
I imagine handling the case where the player tries to designate a harvest area by selecting the side of a cliff and then dragging out to one side or the other would be painful. It can be done, but it would be messy.
I notice that you can select a very “tall” floor if you start or end selecting for your floor at the side of a cliff. But when the villagers build it they will only do the very bottom floor.