Paint area selection is invert?

[sawr]

Hi,
I use ArtRage 5. I use Paint area Selection a lot to apply screentone to my work, but it bugs me everytime that it invert the selection (You paint area to select, it appear as red area. But red area = not selected).
For example, I paint select this area and want to apply some fill.


But when I fill it (or do anything else), it treat that area as 'not selected' while all other area is 'selected' instead.

(Yes, I pretty sure I click inside the red area. I try to fill it with grey color there.)

Should it be another way around? The red area should be 'selected' instead, right?
Is it a bug or intentional or I just miss some setting here?