paint.net is being stupid whenever I work with it

[Yosher]

For example, I have a room.
I draw a line with represents the floor with leaves an empty space below it.
I try to color the empty space and suddenly the entire drawing is that color?

Is this supposed to happen? If not, can anybody tell me how to fix it?

[Ad Bot]

[SpreadsPlague]

the shape is not closed, filling the entire area.

[Pepsidude]

Make sure that the line reaches the edges of the picture, or lower the tolerance of the fillcan.

[Yosher]

the shape is not closed, filling the entire area.

it actually is.
every time.

[LizzyRascal]

Lower the tolerance of the fill tool. But if that doesn't work, then make another layer underneath the line and color it manually.

[Yosher]

Lowering the tolerance helped, thank you both.