Sometimes I can't deactivate the mode of selecting text which is C-SPC. Even if I press it a second time and move the cursor, the text still gets selected. I press C-SPC one more time, it activates and selects the text as I move the cursor. Then if I press C-SPC again and nothing changes except the label says "Mark deactivated" but really it's not. In order to really deactivate, I have to click somewhere in a buffer by mouse.

Is this a bug?