Mask border color question

If I add say a rectangle mask node, the border of the mask is green. If I click on the border and drag it and re-size it it turns red. If I deselect the mask node and re-select it it reverts back to green.
Is the red an indicator that the boarder is currently selected? If so, what affects the border when it is selected? I can not see what keyboard shortcuts that would affect it while it is selected so I am confused as to why it does this red selection indication, if indeed that is what it means.
Thanks!
Is the red an indicator that the boarder is currently selected? If so, what affects the border when it is selected? I can not see what keyboard shortcuts that would affect it while it is selected so I am confused as to why it does this red selection indication, if indeed that is what it means.
Thanks!